Postmark email provider statistics and deliverability context
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According to Live Direct Marketing's daily Tranco top-1M scan (September 22, 2026), Postmark is the email service provider (ESP) for 3,011 domains — 0.47% of 637,585 SPF-publishing domains. Over the last 30 days its share grew by 0.01 pp. Its strongest TLD is .com (56.7% of its domains). Detection: include: mechanisms in the SPF record.
Last updated from the 2026-09-22 DNS snapshot.
What Postmark represents in this dataset
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.
What the 2026-09-22 snapshot shows about Postmark
Across 154 distinct TLDs its top three are .com (56.7%), .org (5.0%), .io (3.0%) — together 64.7% of the 3,011 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, 1,505 domains, 50.0% of them), followed by Microsoft 365 (22.0%). Its share of SPF-publishing domains moved +0.01 pp in 30 days — inside the daily noise of list rotation. 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 (2026-09-22); 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.
Commonly used together with Postmark
What else the same 3,011 domains use — cross-tabulated from the same daily snapshot (2026-09-22).
| Type | Service | Domains | Share of Postmark users |
|---|---|---|---|
| Mailbox | Google Workspace | 1,505 | 50.0% |
| Mailbox | Microsoft 365 | 662 | 22.0% |
| Mailbox | Self-Hosted | 150 | 5.0% |
| Mailbox | Generic / unmatched (mx*.*) | 118 | 3.9% |
| Mailbox | Unknown / Other | 84 | 2.8% |
| Mailbox | Mimecast | 66 | 2.2% |
| ESP | Mailchimp | 418 | 13.9% |
| ESP | SendGrid (Twilio) | 393 | 13.1% |
| ESP | Zendesk | 391 | 13.0% |
| ESP | Amazon SES | 383 | 12.7% |
TLD distribution (top 30 of 154)
Frequently asked questions
How many domains use Postmark?
3,011 domains in the Tranco top-1M use Postmark as their email service provider (ESP) as of September 22, 2026, according to Live Direct Marketing's daily DNS scan.
What is Postmark's market share?
Postmark holds 0.47% of SPF-publishing domains in the Tranco top-1M (snapshot of 2026-09-22). The number is recomputed every day.
Is Postmark growing or declining?
Postmark's share grew by 0.01 percentage points over the last 30 days (as of September 22, 2026).
What are the biggest alternatives to Postmark?
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 2026-09-22).
Largest email service provider (ESP)s in this category
Amazon SES (6.22%) · SendGrid (Twilio) (4.67%) · Mailgun (4.01%) · Zendesk (3.77%) · Mailchimp (3.61%) · Mandrill (3.26%) · HubSpot (3.18%) · Salesforce (2.57%) · Mailjet (Sinch) (2.14%) · Cloudflare Email Routing (1.97%)
Domain sample (top 100 by Tranco rank)
Showing 100 of 3,011 domains.