According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Constant Contact is the email service provider (ESP) for 3,543 domains — 0.57% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Constant Contact is an email marketing platform that provides hosted email-sending infrastructure for small and medium-sized businesses building marketing campaigns and newsletters. It functions as an ESP: it receives mail from its customers' applications and relays it onwards via its own SMTP servers and IP reputation pools.
The SPF footprint of Constant Contact is distributed across many TLDs and appears most often in smaller organisations' DNS records rather than in the largest global brands. It surfaces frequently alongside Microsoft 365, suggesting adoption in SMB environments where managed email and marketing automation are often deployed together. For anyone testing deliverability or diagnosing authentication failures, recognising Constant Contact in a sender's authentication chain signals that mail is routed through a commercial ESP rather than being sent directly from the organisation's own infrastructure.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 3 | 0.1% |
| Top 10,000 | 20 | 0.6% |
| Top 100,000 | 271 | 7.6% |
| Top 1,000,000 | 2,960 | 83.5% |
| Unranked | 289 | 8.2% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 1,302 | 36.7% | |
| .de | 1,068 | 30.1% | |
| .org | 560 | 15.8% | |
| .edu | 99 | 2.8% | |
| .gov | 81 | 2.3% | |
| .net | 77 | 2.2% | |
| .at | 69 | 1.9% | |
| .ch | 65 | 1.8% | |
| .ca | 29 | 0.8% | |
| .eu | 20 | 0.6% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 3,543 domains.
| Type | Service | Domains | Share of Constant Contact users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 1,479 | 41.7% |
| Mailbox | Google Workspace | 391 | 11.0% |
| Mailbox | Self-Hosted | 335 | 9.5% |
| Mailbox | Unknown / Other | 296 | 8.4% |
| Mailbox | Mimecast | 156 | 4.4% |
| Mailbox | Barracuda | 117 | 3.3% |
| ESP | SendGrid (Twilio) | 364 | 10.3% |
| ESP | Amazon SES | 351 | 9.9% |
| ESP | Salesforce | 259 | 7.3% |
| ESP | Mailchimp | 245 | 6.9% |
Constant Contact publishes include statements in SPF records (e.g., include:constantcontact.net) that authorise customers to send mail via Constant Contact's IP pools. Because Constant Contact serves a broad base of smaller organisations across many geographies, individual IP addresses in its sending ranges relay mail for multiple unrelated senders. This shared-pool model means reputation signals—both positive and negative—are distributed across the customer base rather than concentrated in any single sender's reputation score.
See the full Constant Contact data page (KPI cards, trend, sample domains) →
Constant Contact is an email marketing platform that acts as an ESP, meaning it sends email on behalf of customer organisations. It appears in SPF records as an <code>include:</code> statement because customers authorise Constant Contact to relay their mail through Constant Contact's own sending infrastructure.
3,543 domains in the Tranco top-1M use Constant Contact as their email service provider (ESP) as of July 13, 2026 (0.57% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Constant Contact accounts for 0.57% 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.
Constant Contact has been stable — its share moved +0.00 pp over the last 30 days (as of July 13, 2026).
Constant Contact's largest TLD is .com (36.7% of its domains); it appears across 89 TLDs in total.