According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Postmark is the email service provider (ESP) for 2,923 domains — 0.47% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Postmark is a transactional and bulk email delivery service operated by Wildbit, designed to help developers and applications send messages reliably through delegated SMTP infrastructure and managed sender authentication.
Postmark's footprint across the Tranco top-1 million is concentrated among smaller and mid-market .com sites, particularly those also using Google Workspace. For senders, this means joining a long-tail pool of customers whose sending behaviour collectively influences shared IP reputation; for receivers, Postmark's presence signals the likely scale and type of the sending organisation.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 2 | 0.1% |
| Top 10,000 | 51 | 1.7% |
| Top 100,000 | 435 | 14.9% |
| Top 1,000,000 | 2,224 | 76.1% |
| Unranked | 211 | 7.2% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 1,667 | 57.0% | |
| .org | 149 | 5.1% | |
| .io | 85 | 2.9% | |
| .net | 82 | 2.8% | |
| .co.uk | 76 | 2.6% | |
| .nl | 64 | 2.2% | |
| .de | 53 | 1.8% | |
| .co | 48 | 1.6% | |
| .com.au | 47 | 1.6% | |
| .be | 28 | 1.0% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 2,923 domains.
| Type | Service | Domains | Share of Postmark users |
|---|---|---|---|
| Mailbox | Google Workspace | 1,477 | 50.5% |
| Mailbox | Microsoft 365 | 631 | 21.6% |
| Mailbox | Self-Hosted | 138 | 4.7% |
| Mailbox | Generic / unmatched (mx*.*) | 101 | 3.5% |
| Mailbox | Unknown / Other | 94 | 3.2% |
| Mailbox | Mimecast | 63 | 2.2% |
| ESP | Mailchimp | 411 | 14.1% |
| ESP | SendGrid (Twilio) | 397 | 13.6% |
| ESP | Zendesk | 383 | 13.1% |
| ESP | Amazon SES | 381 | 13.0% |
When a sender includes Postmark's SPF record via include:postmarkapp.com, the domain authorises Postmark's infrastructure to send mail on its behalf. This delegation means sender reputation is partly distributed: your emails benefit from Postmark's network standing, but can also be affected by the sending practices of other Postmark customers sharing the same IP space. Understanding this trade-off is essential when evaluating whether to route mail through a third-party provider.
See the full Postmark data page (KPI cards, trend, sample domains) →
Add Postmark's SPF include only if you actively route mail through Postmark; if you do not, the include weakens your SPF record and creates security ambiguity. If you do use Postmark, add its <code>include:postmarkapp.com</code> mechanism to your SPF record, ensuring the total count of DNS lookups stays under ten.
2,923 domains in the Tranco top-1M use Postmark as their email service provider (ESP) as of July 13, 2026 (0.47% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Postmark accounts for 0.47% 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.
Postmark has been stable — its share moved +0.00 pp over the last 30 days (as of July 13, 2026).
Postmark's largest TLD is .com (57.0% of its domains); it appears across 149 TLDs in total.