According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), SMTP.com is the email service provider (ESP) for 1,788 domains — 0.29% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
SMTP.com is an email service provider offering SMTP relay services to organisations that need to delegate outbound email sending to a third party. It is positioned as a specialist relay solution, allowing senders to outsource mail delivery or distribute sending load across multiple providers.
The presence of SMTP.com in SPF records is concentrated among smaller organisations and .com domains, often appearing alongside Microsoft 365 in hybrid mail environments. This pattern suggests SMTP.com serves as a supplementary relay for organisations managing mail across multiple platforms, and its footprint indicates a niche but established position within email infrastructure.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 2 | 0.1% |
| Top 10,000 | 12 | 0.7% |
| Top 100,000 | 183 | 10.2% |
| Top 1,000,000 | 1,396 | 78.1% |
| Unranked | 195 | 10.9% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 1,043 | 58.3% | |
| .org | 123 | 6.9% | |
| .co.uk | 66 | 3.7% | |
| .net | 56 | 3.1% | |
| .ca | 39 | 2.2% | |
| .dk | 38 | 2.1% | |
| .in | 32 | 1.8% | |
| .org.uk | 29 | 1.6% | |
| .nl | 27 | 1.5% | |
| .de | 24 | 1.3% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 1,788 domains.
| Type | Service | Domains | Share of SMTP.com users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 565 | 31.6% |
| Mailbox | Google Workspace | 515 | 28.8% |
| Mailbox | Self-Hosted | 166 | 9.3% |
| Mailbox | Unknown / Other | 87 | 4.9% |
| Mailbox | Mimecast | 82 | 4.6% |
| Mailbox | Proofpoint | 37 | 2.1% |
| ESP | Amazon SES | 221 | 12.4% |
| ESP | SendGrid (Twilio) | 176 | 9.8% |
| ESP | Zendesk | 168 | 9.4% |
| ESP | Mailchimp | 124 | 6.9% |
SMTP.com operates as a shared SMTP relay, meaning your sender reputation sits alongside that of its other customers. Organisations using SMTP.com should actively monitor delivery metrics, feedback loops, and spam complaint rates reported by the platform. Proper SPF, DKIM, and DMARC alignment is essential to separate your reputation signals from the broader customer base and to flag any negative feedback that may originate from other senders on the platform.
See the full SMTP.com data page (KPI cards, trend, sample domains) →
SMTP.com in your SPF record indicates you are delegating SMTP sending to their service. This is typical for organisations using a dedicated email relay, and your sender reputation becomes partially shared with their platform; you should monitor delivery reports to ensure your sending is not adversely affected by other customers' behaviour.
1,788 domains in the Tranco top-1M use SMTP.com as their email service provider (ESP) as of July 13, 2026 (0.29% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
SMTP.com accounts for 0.29% 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.
SMTP.com's largest TLD is .com (58.3% of its domains); it appears across 122 TLDs in total.