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According to Live Direct Marketing's daily Tranco top-1M scan (July 26, 2026), Constant Contact is the email service provider (ESP) for 3,699 domains — 0.59% of 630,738 SPF-publishing domains. Its share has been stable over the last 30 days. Its strongest TLD is .com (36.6% of its domains). Detection: include: mechanisms in the SPF record.
Last updated from the 2026-07-26 DNS snapshot.
US small-business newsletter platform.
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 90 distinct TLDs its top three are .com (36.6%), .de (30.0%), .org (15.9%) — together 82.6% of the 3,699 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 Microsoft 365 (Mailbox, 1,563 domains, 42.3% of them), followed by Google Workspace (11.0%). 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 3,699 domains use — cross-tabulated from the same daily snapshot (2026-07-26).
| Type | Service | Domains | Share of Constant Contact users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 1,563 | 42.3% |
| Mailbox | Google Workspace | 408 | 11.0% |
| Mailbox | Self-Hosted | 345 | 9.3% |
| Mailbox | Unknown / Other | 307 | 8.3% |
| Mailbox | Mimecast | 155 | 4.2% |
| Mailbox | Barracuda | 121 | 3.3% |
| ESP | SendGrid (Twilio) | 374 | 10.1% |
| ESP | Amazon SES | 361 | 9.8% |
| ESP | Salesforce | 273 | 7.4% |
| ESP | Mailchimp | 252 | 6.8% |
3,699 domains in the Tranco top-1M use Constant Contact as their email service provider (ESP) as of July 26, 2026, according to Live Direct Marketing's daily DNS scan.
Constant Contact holds 0.59% of SPF-publishing domains in the Tranco top-1M (snapshot of 2026-07-26). The number is recomputed every day.
Constant Contact'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 3,699 domains.