StackMail email provider statistics and deliverability context
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According to Live Direct Marketing's daily Tranco top-1M scan (September 19, 2026), StackMail is the email service provider (ESP) for 1,273 domains — 0.20% of 642,799 SPF-publishing domains. Its strongest TLD is .com (45.3% of its domains). Detection: include: mechanisms in the SPF record.
Last updated from the 2026-09-19 DNS snapshot.
What StackMail represents in this dataset
UK shared webmail used by registrars/resellers.
Directory category: Mailbox. 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 2026-09-19 snapshot shows about StackMail
Across 82 distinct TLDs its top three are .com (45.3%), .co.uk (26.3%), .net (3.8%) — together 75.4% of the 1,273 domains, which makes the footprint narrow — three TLDs cover most of it, which is typical of a regional or single-market operator. The service most often observed on the same domains is StackMail (UK mailbox) (Mailbox, 1,066 domains, 83.7% of them), followed by Microsoft 365 (6.8%). 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 (2026-09-19); 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 StackMail
What else the same 1,273 domains use — cross-tabulated from the same daily snapshot (2026-09-19).
| Type | Service | Domains | Share of StackMail users |
|---|---|---|---|
| Mailbox | StackMail (UK mailbox) | 1,066 | 83.7% |
| Mailbox | Microsoft 365 | 87 | 6.8% |
| Mailbox | Google Workspace | 71 | 5.6% |
| Mailbox | Self-Hosted | 15 | 1.2% |
| Mailbox | Unknown / Other | 7 | 0.5% |
| Mailbox | Barracuda | 4 | 0.3% |
| ESP | MailerLite | 22 | 1.7% |
| ESP | Mandrill | 18 | 1.4% |
| ESP | Mailchimp | 18 | 1.4% |
| ESP | Amazon SES | 16 | 1.3% |
TLD distribution (top 30 of 82)
Frequently asked questions
How many domains use StackMail?
1,273 domains in the Tranco top-1M use StackMail as their email service provider (ESP) as of September 19, 2026, according to Live Direct Marketing's daily DNS scan.
What is StackMail's market share?
StackMail holds 0.20% of SPF-publishing domains in the Tranco top-1M (snapshot of 2026-09-19). The number is recomputed every day.
What are the biggest alternatives to StackMail?
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 2026-09-19).
Largest email service provider (ESP)s in this category
Amazon SES (6.20%) · SendGrid (Twilio) (4.65%) · Mailgun (4.00%) · Zendesk (3.76%) · Mailchimp (3.59%) · Mandrill (3.25%) · HubSpot (3.15%) · Salesforce (2.55%) · Mailjet (Sinch) (2.13%) · Cloudflare Email Routing (1.96%)
Domain sample (top 100 by Tranco rank)
Showing 100 of 1,273 domains.