According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), emSMTP is the email service provider (ESP) for 141 domains — 0.02% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
emSMTP is an email relay service that accepts SMTP connections and delivers messages to recipient mail servers on behalf of sending organisations. It provides mail delivery infrastructure for senders who choose to route messages through its platform.
Across the public internet, emSMTP appears predominantly in the SPF records of smaller and mid-market organisations, rather than among the largest global brands. Its deployment is internationally distributed across many top-level domains, concentrated primarily in .com addresses, and it frequently appears alongside Microsoft 365 mail infrastructure. For deliverability purposes, emSMTP is a routinely deployed relay service in the mid-market segment; its presence in SPF records reflects a standard infrastructure choice rather than a reputation concern.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 0 | 0.0% |
| Top 100,000 | 30 | 21.3% |
| Top 1,000,000 | 106 | 75.2% |
| Unranked | 5 | 3.5% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 37 | 26.2% | |
| .de | 35 | 24.8% | |
| .at | 11 | 7.8% | |
| .ch | 8 | 5.7% | |
| .co.uk | 8 | 5.7% | |
| .nl | 5 | 3.5% | |
| .it | 4 | 2.8% | |
| .com.au | 3 | 2.1% | |
| .net | 3 | 2.1% | |
| .ru | 3 | 2.1% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 141 domains.
| Type | Service | Domains | Share of emSMTP users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 62 | 44.0% |
| Mailbox | Google Workspace | 28 | 19.9% |
| Mailbox | Unknown / Other | 9 | 6.4% |
| Mailbox | Generic / unmatched (mx*.*) | 8 | 5.7% |
| Mailbox | Self-Hosted | 6 | 4.3% |
| Mailbox | Hornetsecurity | 4 | 2.8% |
| ESP | Emarsys (SAP) | 118 | 83.7% |
| ESP | Zendesk | 21 | 14.9% |
| ESP | Amazon SES | 15 | 10.6% |
| ESP | Mailjet (Sinch) | 12 | 8.5% |
When emSMTP appears in a domain's SPF record, it is explicitly authorised as a mail relay for that sender. The prevalence of emSMTP alongside Microsoft 365 configurations indicates that many mid-market organisations authorise multiple relays within their mail infrastructure, a deployment pattern that carries no inherent deliverability risk provided all authorised relays maintain clean sending practices and sender reputation. Organisations supporting multiple relays should ensure their SPF records remain concise and regularly audit which relays remain active, as unnecessary include mechanisms increase complexity and potential attack surface.
See the full emSMTP data page (KPI cards, trend, sample domains) →
emSMTP is an SMTP relay service that organisations can authorise to send mail on their behalf. It is commonly found deployed alongside Microsoft 365, indicating that many organisations use it as a supplementary mail relay within their broader mail infrastructure.
141 domains in the Tranco top-1M use emSMTP as their email service provider (ESP) as of July 13, 2026 (0.02% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
emSMTP accounts for 0.02% of SPF-publishing domains in the top 1M. Whether you should seed a test mailbox there depends on how much of your audience it represents — the co-usage table above shows the services it appears alongside most.
emSMTP's largest TLD is .com (26.2% of its domains); it appears across 30 TLDs in total.