esp
According to Live Direct Marketing's daily Tranco top-1M scan (July 26, 2026), Postmark is the email service provider (ESP) for 2,995 domains — 0.47% of 630,738 SPF-publishing domains. Its share has been stable over the last 30 days. Its strongest TLD is .com (57.3% of its domains). Detection: include: mechanisms in the SPF record.
Last updated from the 2026-07-26 DNS snapshot.
Transactional email service known for high deliverability and developer UX.
Directory category: Esp. The classification comes from include: mechanisms in the SPF record. It describes observed DNS infrastructure, not a commercial relationship and not the placement of any individual message.
Across 150 distinct TLDs its top three are .com (57.3%), .org (5.1%), .net (2.9%) — together 65.3% of the 2,995 domains, which makes the footprint moderately concentrated, with a recognisable home market. The service most often observed on the same domains is Google Workspace (Mailbox, 1,499 domains, 50.1% of them), followed by Microsoft 365 (21.8%). Its share of SPF-publishing domains has not moved measurably in 30 days. Directly comparable by the same detection rule: Amazon SES, SendGrid (Twilio), Mailgun. Ranking between them reflects what is published in DNS, not delivery quality or volume sent. All figures come from a single daily DNS snapshot (2026-07-26); a domain appears here when its published records match the include: mechanisms in the SPF record rule, which is an infrastructure fact, not a commercial relationship.
What else the same 2,995 domains use — cross-tabulated from the same daily snapshot (2026-07-26).
| Type | Service | Domains | Share of Postmark users |
|---|---|---|---|
| Mailbox | Google Workspace | 1,499 | 50.1% |
| Mailbox | Microsoft 365 | 652 | 21.8% |
| Mailbox | Self-Hosted | 143 | 4.8% |
| Mailbox | Generic / unmatched (mx*.*) | 115 | 3.8% |
| Mailbox | Unknown / Other | 91 | 3.0% |
| Mailbox | Mimecast | 67 | 2.2% |
| ESP | Mailchimp | 415 | 13.9% |
| ESP | SendGrid (Twilio) | 399 | 13.3% |
| ESP | Zendesk | 389 | 13.0% |
| ESP | Amazon SES | 382 | 12.8% |
2,995 domains in the Tranco top-1M use Postmark as their email service provider (ESP) as of July 26, 2026, according to Live Direct Marketing's daily DNS scan.
Postmark holds 0.47% of SPF-publishing domains in the Tranco top-1M (snapshot of 2026-07-26). The number is recomputed every day.
Postmark's share has been stable over the last 30 days (±0.01 pp).
The largest email service provider (ESP)s in the same category by Tranco top-1M share are: Amazon SES, SendGrid (Twilio), Mailgun, Zendesk, Mailchimp (as of 2026-07-26).
Amazon SES (6.17%) · SendGrid (Twilio) (4.76%) · Mailgun (4.11%) · Zendesk (3.83%) · Mailchimp (3.70%) · Mandrill (3.36%) · HubSpot (3.19%) · Salesforce (2.62%) · Mailjet (Sinch) (2.13%) · Cloudflare Email Routing (1.82%)
Showing 100 of 2,995 domains.