Company lists · Data refreshed September 2026
Top 23 Smtp relay services based in the United States
RevenueBase identified 89 company matches for smtp relay services associated with the United States as of September 2026 and tracks 876 professional contacts across them, including 269 with verified work emails. New York is the largest hub.
This list covers company matches for smtp relay services associated with the United States, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 22, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.
The 23 largest smtp relay services based in the United States
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 190 contacts → | ||||
Exact match “Sinch Mailgun is the leading email delivery service for businesses around the world.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 2 | 38 contacts → | ||||
Exact match “SendGrid is a proven cloud-based customer communication platform that successfully delivers over 45 billion emails each month for Internet and mobile-based customers like Airbnb…” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 3 | 37 contacts → | ||||
Exact match “Maildoso provides high-quality SMTP and Google mailboxes built for cold email deliverability.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 4 | 31 contacts → | ||||
Exact match “The home for all things mail.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 5 | 29 contacts → | ||||
Exact match “Folderly is an all-in-one email deliverability platform to supercharge your email performance.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 6 | 15 contacts → | ||||
Exact match “Spambrella is a Worldwide email content control security ‘software as a service’ (SaaS) provider.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 7 | 13 contacts → | ||||
Exact match “SocketLabs is an email service provider with a full suite of email delivery, management, and performance analysis tools.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 8 | 12 contacts → | ||||
Exact match “Reliable and Secure email hosting services for SMB and Enterprise.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 9 | 11 contacts → | ||||
Exact match “Senders is focused on email infrastructure, email scaling, email deliverability, and email sendability.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 10 | 11 contacts → | ||||
Exact match “Mail2World designs, delivers and supports a technology-leading and award-winning suite of carrier-class, Web-based email messaging and collaboration services.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 11 | 10 contacts → | ||||
Exact match “As spam filters tighten, 52% of business emails go unseen, crippling sales and collections for B2B companies.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 12 | 10 contacts → | ||||
Exact match “SH supports companies by improving email deliverability, detecting and mitigating security risks, and architecting sending infrastructure for sustainable scale and growth.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 13 | 10 contacts → | ||||
Exact match “Our specialization: Ensure reliable and efficient delivery of emails.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 14 | 8 contacts → | ||||
Exact match “The email delivery service that people actually like.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 15 | 7 contacts → | ||||
Exact match “Egressif provides managed email deliverability services businesses.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 16 | 6 contacts → | ||||
Exact match “Effortless Email Forwarding” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 17 | 5 contacts → | ||||
Exact match “Since 2001, EmailOpen™ has been a leader in innovative electronic mail solutions, delivering proven and measurable results to the internal communication and direct marketing…” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 18 | 5 contacts → | ||||
Exact match “Acquired by GoDaddy in 2014, Mad Mimi is a lovely, simple email service that lets you create, send and track email newsletters.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 19 | 3 contacts → | ||||
Exact match “Amply is re-engineering email delivery with our API, providing unparalleled reliability at scale.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 20 | 3 contacts → | ||||
Exact match “At Inbox Navigator, we pride ourselves on being the email superheroes you need to ensure your emails reach the inbox as they should.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 21 | 2 contacts → | ||||
Exact match “With over 30 years of combined industry experienced, we have helped businesses mitigate issues, improve deliverability, rebuild, repair, and maintain their reputation.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 22 | 1 contacts → | ||||
Exact match “With over two decades of expertise in email marketing and deliverability, we are the go-to professionals for getting your emails into the inbox.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
| 23 | 1 contacts → | ||||
Exact match “Inbox Genie is an enterprise-level Email Service Provider (ESP) created for high volume, strategic email senders.” Recorded in the RevenueBase company graph · Sep 22, 2026 · View company records in RevenueBase | |||||
RevenueBase SmartSearch
Describe a niche business in your own words. RevenueBase SmartSearch compares the meaning of your description with company business descriptions compiled in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit.
This list uses Exact for “smtp relay services”. Each Exact match badge shows membership in that saved search; it is not an individual similarity score or a service-quality rating. Recorded descriptions are shown where available.
Showing 23 of 89 smtp relay services based in the United States
See the full list, filter by size, metro and specialty, and access 269 tracked professional contacts with verified work emails. Direct dials are available where recorded.
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Smtp relay services based in the United States at a glance
As of Sep 22, 2026Companies by employee count
Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 89 companies.
How this list was built
The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
- What qualifies
- Company records associated with the United States whose business descriptions match “smtp relay services” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
- RevenueBase SmartSearch
- Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
- Public preview
- The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
- Match quality
- RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
- Ranking
- Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
- Verification
- Every displayed company carries at least one verified work email. RevenueBase tracks 269 professional contacts with verified work emails across the full matched dataset. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
- Refresh
- This page's figures were pulled from the company graph on September 22, 2026. Lists refresh periodically as the graph is re-checked.
- Record context
- Company records and descriptions can change. Check the company's website for its current services and locations.
Frequently asked
What is RevenueBase SmartSearch?
RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “smtp relay services”; each Exact match badge shows search membership, not an individual similarity or quality score.
How many smtp relay services are there based in the United States?
RevenueBase identified 89 company matches for smtp relay services associated with the United States as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.
What is the largest company on this list?
Sinch Mailgun tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.
Which city has the most smtp relay services?
New York leads with 7 company records, followed by San Francisco (4) and Austin (3).
How do I get contact information for these companies?
A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 269 professional contacts with verified work emails tracked across these 89 companies; direct dials are available where recorded.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 22, 2026.
Ready to reach these companies? Verified emails and direct dials for all 89 smtp relay services based in the United States. Start with a free account, no credit card.
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About this data
RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase SmartSearch, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.
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- New lists
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Company intelligence · public preview
Top 23 smtp relay services based in the United States
Find companies in any niche.
Describe the businesses you want in your own words. RevenueBase SmartSearch matches company descriptions by meaning.
RevenueBase records 89 matching company records for smtp relay services based in the United States, with 876 tracked contacts and 269 verified work emails.
This public preview shows 23 selected records ordered by tracked contacts. RevenueBase SmartSearch finds company descriptions that match by meaning at Exact. Snapshot: September 22, 2026.
RevenueBase compiles business descriptions for niche-company discovery; each row shows a recorded excerpt where available. Adapt this search to find the companies and contacts you want.
Top 23 smtp relay services based in the United States
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
| # | Company | Headquarters on record | Reported employees | RevenueBase SmartSearch | Tracked contacts |
|---|---|---|---|---|---|
| 1 |  Sinch Mailgunmailgun.comHQ: San Antonio, TX, United StatesReported employees: 201-500 | San Antonio, TX, United States | 201-500 | Exact match | 190 contacts → |
“Sinch Mailgun is the leading email delivery service for businesses around the world.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 2 | Sendgridsendgrid.com HQ: Denver, CO, United StatesReported employees: 201-500 | Denver, CO, United States | 201-500 | Exact match | 38 contacts → |
“SendGrid is a proven cloud-based customer communication platform that successfully delivers over 45 billion emails each month for Internet and mobile-based customers like Airbnb…” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 3 |  Maildosomaildoso.aiHQ: Granite Bay, CA, United StatesReported employees: 11-50 | Granite Bay, CA, United States | 11-50 | Exact match | 37 contacts → |
“Maildoso provides high-quality SMTP and Google mailboxes built for cold email deliverability.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 4 |  mailing.commailing.comHQ: Phoenix, AZ, United StatesReported employees: 51-200 | Phoenix, AZ, United States | 51-200 | Exact match | 31 contacts → |
“The home for all things mail.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 5 |  Folderly INCfolderly.comHQ: Dover, DE, United StatesReported employees: 51-200 | Dover, DE, United States | 51-200 | Exact match | 29 contacts → |
“Folderly is an all-in-one email deliverability platform to supercharge your email performance.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 6 |  Spambrellaspambrella.comHQ: Dover, DE, United StatesReported employees: 51-200 | Dover, DE, United States | 51-200 | Exact match | 15 contacts → |
“Spambrella is a Worldwide email content control security ‘software as a service’ (SaaS) provider.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 7 |  Socketlabssocketlabs.comHQ: Wayne, PA, United StatesReported employees: 11-50 | Wayne, PA, United States | 11-50 | Exact match | 13 contacts → |
“SocketLabs is an email service provider with a full suite of email delivery, management, and performance analysis tools.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 8 |  Duocircleduocircle.comHQ: San Diego, CA, United StatesReported employees: 11-50 | San Diego, CA, United States | 11-50 | Exact match | 12 contacts → |
“Reliable and Secure email hosting services for SMB and Enterprise.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 9 |  Senderssenders.coHQ: Brooklyn, NY, United StatesReported employees: 11-50 | Brooklyn, NY, United States | 11-50 | Exact match | 11 contacts → |
“Senders is focused on email infrastructure, email scaling, email deliverability, and email sendability.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 10 |  Mail2world, INCmail2world.netHQ: Los Angeles, CA, United StatesReported employees: 51-200 | Los Angeles, CA, United States | 51-200 | Exact match | 11 contacts → |
“Mail2World designs, delivers and supports a technology-leading and award-winning suite of carrier-class, Web-based email messaging and collaboration services.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 11 |  Mission Inboxmissioninbox.comHQ: San Francisco, CA, United StatesReported employees: 1-10 | San Francisco, CA, United States | 1-10 | Exact match | 10 contacts → |
“As spam filters tighten, 52% of business emails go unseen, crippling sales and collections for B2B companies.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 12 |  SH Consultingsh.consultingHQ: Miami, FL, United StatesReported employees: 1-10 | Miami, FL, United States | 1-10 | Exact match | 10 contacts → |
“SH supports companies by improving email deliverability, detecting and mitigating security risks, and architecting sending infrastructure for sustainable scale and growth.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 13 |  Xpand Outreachxpandoutreach.comHQ: Denver, CO, United StatesReported employees: 1-10 | Denver, CO, United States | 1-10 | Exact match | 10 contacts → |
“Our specialization: Ensure reliable and efficient delivery of emails.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 14 |  Postmarkpostmarkapp.comHQ: Chicago, IL, United StatesReported employees: 11-50 | Chicago, IL, United States | 11-50 | Exact match | 8 contacts → |
“The email delivery service that people actually like.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 15 |  Egressifegressif.ioHQ: Sheridan, WY, United StatesReported employees: 1-10 | Sheridan, WY, United States | 1-10 | Exact match | 7 contacts → |
“Egressif provides managed email deliverability services businesses.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 16 | Improvmximprovmx.com HQ: New York, NY, United StatesReported employees: 1-10 | New York, NY, United States | 1-10 | Exact match | 6 contacts → |
“Effortless Email Forwarding” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 17 |  Emailopenemailopen.comHQ: Malibu, CA, United StatesReported employees: 11-50 | Malibu, CA, United States | 11-50 | Exact match | 5 contacts → |
“Since 2001, EmailOpen™ has been a leader in innovative electronic mail solutions, delivering proven and measurable results to the internal communication and direct marketing…” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 18 |  MAD Mimimadmimi.comHQ: Scottsdale, AZ, United StatesReported employees: 11-50 | Scottsdale, AZ, United States | 11-50 | Exact match | 5 contacts → |
“Acquired by GoDaddy in 2014, Mad Mimi is a lovely, simple email service that lets you create, send and track email newsletters.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 19 |  AMPLYsendamply.comHQ: San Diego, CA, United StatesReported employees: 1-10 | San Diego, CA, United States | 1-10 | Exact match | 3 contacts → |
“Amply is re-engineering email delivery with our API, providing unparalleled reliability at scale.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 20 |  Inbox Navigatorinboxnavigator.comHQ: San Francisco, CA, United StatesReported employees: 1-10 | San Francisco, CA, United States | 1-10 | Exact match | 3 contacts → |
“At Inbox Navigator, we pride ourselves on being the email superheroes you need to ensure your emails reach the inbox as they should.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 21 |  Start Inboxingstartinboxing.comHQ: Orlando, FL, United StatesReported employees: 1-10 | Orlando, FL, United States | 1-10 | Exact match | 2 contacts → |
“With over 30 years of combined industry experienced, we have helped businesses mitigate issues, improve deliverability, rebuild, repair, and maintain their reputation.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 22 |  JET Agency Groupjetmarketingandconsulting.comHQ: Seattle, WA, United StatesReported employees: 11-50 | Seattle, WA, United States | 11-50 | Exact match | 1 contacts → |
“With over two decades of expertise in email marketing and deliverability, we are the go-to professionals for getting your emails into the inbox.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 23 | Inbox Genie LLCinboxgenie.com HQ: Charlotte, NC, United StatesReported employees: 1-10 | Charlotte, NC, United States | 1-10 | Exact match | 1 contacts → |
“Inbox Genie is an enterprise-level Email Service Provider (ESP) created for high volume, strategic email senders.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
Showing 23 of 89 company matches
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Smtp relay services: dataset insights
September 22, 2026These summaries describe recorded coverage in this saved dataset. This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Reported company sizes
88 records in the displayed employee bands.
1 matching records are outside the displayed bands or do not have a displayed size. Bars show shares of the displayed bands.
Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 89 companies.
How this company list was built
Describe a niche in your own words: companies installing commercial solar, or manufacturers of sustainable packaging. RevenueBase SmartSearch finds companies whose compiled business descriptions match by meaning. This list is one saved example to adapt.
Where the company descriptions come from
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
RevenueBase SmartSearch matching settings
- Exact
- Closest fits to the business described.
- Similar
- Similar businesses with a wider range of fits.
- Related
- Related businesses in and around the category.
- Broad
- A broader set of businesses connected to the description.
RevenueBase SmartSearch · Exact match identifies inclusion in this search's closest semantic matching setting. It is not a per-company confidence score, a literal keyword match, or a quality endorsement.
Selection, ordering and scope
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Recorded company descriptions support research; check company websites for current services. The selected preview is ordered by tracked contacts and is not a list of the best service providers.
Snapshot: September 22, 2026.
RevenueBase is a B2B data infrastructure company. Its September 3, 2026 published methodology describes a graph of 60 million companies and 398.9 million professional contacts; these platform figures differ from this page's totals. Published methodology ↗
Questions about this company list
What does Exact match mean for smtp relay services?
The separate RevenueBase SmartSearch column identifies inclusion at the closest semantic matching preset. It is not a literal keyword match, a per-company confidence score or a quality endorsement. Changing the search form opens a new search in RevenueBase; it does not reclassify these saved rows.
How many smtp relay services did RevenueBase find based in the United States?
The saved snapshot records 89 matching company records, 876 tracked contacts and 269 verified emails. The public preview displays 23 selected records.
Where do the company descriptions come from?
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
How are the public companies ordered?
The selected public records are ordered by contacts tracked in RevenueBase, highest first. Contact coverage is a prospecting measure, not an assessment of the company's services or quality.
How can I get contact information?
Select a company's contact count to open its filtered contacts in RevenueBase. Free signup is required and includes 500 credits and limited free results. Verified emails, direct dials and mobile numbers depend on available coverage.
How current is this list?
Snapshot: September 22, 2026. Review each company's website for current services and locations. A recorded business description does not establish that every company offers every service named in the search.
What do headquarters and employee bands mean?
These are recorded company-level fields, rather than a map of every branch or a count of specialists. Missing headquarters or employee bands are labeled; older records may show a location separately from recorded headquarters.
Build your next target company list
Adapt this niche search and work with available contacts in RevenueBase.
Related lists
Smtp relay services by geography
Browse the directory
Cite this list
RevenueBase Data Team. Top 23 smtp relay services based in the United States. Snapshot: September 22, 2026. https://revenuebase.ai/companies/smtp-relay-services/united-states.
This is a selected public preview of saved company records, rather than an independently verified census. Open the source page ↗
More company lists
- All company lists
- Lists by location
- Lists A-Z
- New lists
- Smtp relay services based in India
- AI companies based in the United States
- Cybersecurity companies based in the United States
- Manufacturing companies based in the United States
- Media companies based in the United States
- Oil and gas companies based in the United States
Company intelligence · public preview
Top 23 smtp relay services based in the United States
RevenueBase records 89 matching company records for smtp relay services based in the United States, with 876 tracked contacts and 269 verified work emails.
This public preview shows 23 selected records ordered by tracked contacts. RevenueBase SmartSearch finds company descriptions that match by meaning at Exact. Snapshot: September 22, 2026.
RevenueBase compiles business descriptions for niche-company discovery; each row shows a recorded excerpt where available. Adapt this search to find the companies and contacts you want.
Top 23 smtp relay services based in the United States
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
| # | Company | Headquarters on record | Reported employees | RevenueBase SmartSearch | Tracked contacts |
|---|---|---|---|---|---|
| 1 | Sinch Mailgunmailgun.com HQ: San Antonio, TX, United StatesReported employees: 201-500 | San Antonio, TX, United States | 201-500 | Exact match | 190 contacts → |
“Sinch Mailgun is the leading email delivery service for businesses around the world.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 2 | Sendgridsendgrid.com HQ: Denver, CO, United StatesReported employees: 201-500 | Denver, CO, United States | 201-500 | Exact match | 38 contacts → |
“SendGrid is a proven cloud-based customer communication platform that successfully delivers over 45 billion emails each month for Internet and mobile-based customers like Airbnb…” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 3 | Maildosomaildoso.ai HQ: Granite Bay, CA, United StatesReported employees: 11-50 | Granite Bay, CA, United States | 11-50 | Exact match | 37 contacts → |
“Maildoso provides high-quality SMTP and Google mailboxes built for cold email deliverability.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 4 | mailing.commailing.com HQ: Phoenix, AZ, United StatesReported employees: 51-200 | Phoenix, AZ, United States | 51-200 | Exact match | 31 contacts → |
“The home for all things mail.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 5 | Folderly INCfolderly.com HQ: Dover, DE, United StatesReported employees: 51-200 | Dover, DE, United States | 51-200 | Exact match | 29 contacts → |
“Folderly is an all-in-one email deliverability platform to supercharge your email performance.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 6 | Spambrellaspambrella.com HQ: Dover, DE, United StatesReported employees: 51-200 | Dover, DE, United States | 51-200 | Exact match | 15 contacts → |
“Spambrella is a Worldwide email content control security ‘software as a service’ (SaaS) provider.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 7 | Socketlabssocketlabs.com HQ: Wayne, PA, United StatesReported employees: 11-50 | Wayne, PA, United States | 11-50 | Exact match | 13 contacts → |
“SocketLabs is an email service provider with a full suite of email delivery, management, and performance analysis tools.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 8 | Duocircleduocircle.com HQ: San Diego, CA, United StatesReported employees: 11-50 | San Diego, CA, United States | 11-50 | Exact match | 12 contacts → |
“Reliable and Secure email hosting services for SMB and Enterprise.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 9 | Senderssenders.co HQ: Brooklyn, NY, United StatesReported employees: 11-50 | Brooklyn, NY, United States | 11-50 | Exact match | 11 contacts → |
“Senders is focused on email infrastructure, email scaling, email deliverability, and email sendability.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 10 | Mail2world, INCmail2world.net HQ: Los Angeles, CA, United StatesReported employees: 51-200 | Los Angeles, CA, United States | 51-200 | Exact match | 11 contacts → |
“Mail2World designs, delivers and supports a technology-leading and award-winning suite of carrier-class, Web-based email messaging and collaboration services.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 11 | Mission Inboxmissioninbox.com HQ: San Francisco, CA, United StatesReported employees: 1-10 | San Francisco, CA, United States | 1-10 | Exact match | 10 contacts → |
“As spam filters tighten, 52% of business emails go unseen, crippling sales and collections for B2B companies.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 12 | SH Consultingsh.consulting HQ: Miami, FL, United StatesReported employees: 1-10 | Miami, FL, United States | 1-10 | Exact match | 10 contacts → |
“SH supports companies by improving email deliverability, detecting and mitigating security risks, and architecting sending infrastructure for sustainable scale and growth.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 13 | Xpand Outreachxpandoutreach.com HQ: Denver, CO, United StatesReported employees: 1-10 | Denver, CO, United States | 1-10 | Exact match | 10 contacts → |
“Our specialization: Ensure reliable and efficient delivery of emails.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 14 | Postmarkpostmarkapp.com HQ: Chicago, IL, United StatesReported employees: 11-50 | Chicago, IL, United States | 11-50 | Exact match | 8 contacts → |
“The email delivery service that people actually like.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 15 | Egressifegressif.io HQ: Sheridan, WY, United StatesReported employees: 1-10 | Sheridan, WY, United States | 1-10 | Exact match | 7 contacts → |
“Egressif provides managed email deliverability services businesses.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 16 | Improvmximprovmx.com HQ: New York, NY, United StatesReported employees: 1-10 | New York, NY, United States | 1-10 | Exact match | 6 contacts → |
“Effortless Email Forwarding” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 17 | Emailopenemailopen.com HQ: Malibu, CA, United StatesReported employees: 11-50 | Malibu, CA, United States | 11-50 | Exact match | 5 contacts → |
“Since 2001, EmailOpen™ has been a leader in innovative electronic mail solutions, delivering proven and measurable results to the internal communication and direct marketing…” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 18 | MAD Mimimadmimi.com HQ: Scottsdale, AZ, United StatesReported employees: 11-50 | Scottsdale, AZ, United States | 11-50 | Exact match | 5 contacts → |
“Acquired by GoDaddy in 2014, Mad Mimi is a lovely, simple email service that lets you create, send and track email newsletters.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 19 | AMPLYsendamply.com HQ: San Diego, CA, United StatesReported employees: 1-10 | San Diego, CA, United States | 1-10 | Exact match | 3 contacts → |
“Amply is re-engineering email delivery with our API, providing unparalleled reliability at scale.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 20 | Inbox Navigatorinboxnavigator.com HQ: San Francisco, CA, United StatesReported employees: 1-10 | San Francisco, CA, United States | 1-10 | Exact match | 3 contacts → |
“At Inbox Navigator, we pride ourselves on being the email superheroes you need to ensure your emails reach the inbox as they should.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 21 | Start Inboxingstartinboxing.com HQ: Orlando, FL, United StatesReported employees: 1-10 | Orlando, FL, United States | 1-10 | Exact match | 2 contacts → |
“With over 30 years of combined industry experienced, we have helped businesses mitigate issues, improve deliverability, rebuild, repair, and maintain their reputation.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 22 | JET Agency Groupjetmarketingandconsulting.com HQ: Seattle, WA, United StatesReported employees: 11-50 | Seattle, WA, United States | 11-50 | Exact match | 1 contacts → |
“With over two decades of expertise in email marketing and deliverability, we are the go-to professionals for getting your emails into the inbox.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 23 | Inbox Genie LLCinboxgenie.com HQ: Charlotte, NC, United StatesReported employees: 1-10 | Charlotte, NC, United States | 1-10 | Exact match | 1 contacts → |
“Inbox Genie is an enterprise-level Email Service Provider (ESP) created for high volume, strategic email senders.” Recorded description excerpt · September 22, 2026Open company data in RevenueBase ↗Free signup required. | |||||
Showing 23 of 89 company matches
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Smtp relay services: dataset insights
September 22, 2026These summaries describe recorded coverage in this saved dataset. This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Reported company sizes
88 records in the displayed employee bands.
1 matching records are outside the displayed bands or do not have a displayed size. Bars show shares of the displayed bands.
Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 89 companies.
How this company list was built
Describe a niche in your own words: companies installing commercial solar, or manufacturers of sustainable packaging. RevenueBase SmartSearch finds companies whose compiled business descriptions match by meaning. This list is one saved example to adapt.
Where the company descriptions come from
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
RevenueBase SmartSearch matching settings
- Exact
- Closest fits to the business described.
- Similar
- Similar businesses with a wider range of fits.
- Related
- Related businesses in and around the category.
- Broad
- A broader set of businesses connected to the description.
RevenueBase SmartSearch · Exact match identifies inclusion in this search's closest semantic matching setting. It is not a per-company confidence score, a literal keyword match, or a quality endorsement.
Selection, ordering and scope
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Recorded company descriptions support research; check company websites for current services. The selected preview is ordered by tracked contacts and is not a list of the best service providers.
Snapshot: September 22, 2026.
RevenueBase is a B2B data infrastructure company. Its September 3, 2026 published methodology describes a graph of 60 million companies and 398.9 million professional contacts; these platform figures differ from this page's totals. Published methodology ↗
Questions about this company list
What does Exact match mean for smtp relay services?
The separate RevenueBase SmartSearch column identifies inclusion at the closest semantic matching preset. It is not a literal keyword match, a per-company confidence score or a quality endorsement. Changing the search form opens a new search in RevenueBase; it does not reclassify these saved rows.
How many smtp relay services did RevenueBase find based in the United States?
The saved snapshot records 89 matching company records, 876 tracked contacts and 269 verified emails. The public preview displays 23 selected records.
Where do the company descriptions come from?
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
How are the public companies ordered?
The selected public records are ordered by contacts tracked in RevenueBase, highest first. Contact coverage is a prospecting measure, not an assessment of the company's services or quality.
How can I get contact information?
Select a company's contact count to open its filtered contacts in RevenueBase. Free signup is required and includes 500 credits and limited free results. Verified emails, direct dials and mobile numbers depend on available coverage.
How current is this list?
Snapshot: September 22, 2026. Review each company's website for current services and locations. A recorded business description does not establish that every company offers every service named in the search.
What do headquarters and employee bands mean?
These are recorded company-level fields, rather than a map of every branch or a count of specialists. Missing headquarters or employee bands are labeled; older records may show a location separately from recorded headquarters.
Build your next target company list
Adapt this niche search and work with available contacts in RevenueBase.
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Cite this list
RevenueBase Data Team. Top 23 smtp relay services based in the United States. Snapshot: September 22, 2026. https://revenuebase.ai/companies/smtp-relay-services/united-states.
This is a selected public preview of saved company records, rather than an independently verified census. Open the source page ↗
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