According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Sailthru is the email service provider (ESP) for 634 domains — 0.10% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Sailthru is a commercial email service provider specialising in marketing automation and customer communication infrastructure for enterprise organisations. It offers managed email sending, campaign analytics, and personalisation capabilities, enabling large senders to delegate delivery operations whilst maintaining their brand and domain identity.
Sailthru's footprint—detected through SPF records across high-traffic, well-known sites, predominantly in the .com namespace, and frequently alongside Google Workspace deployments—indicates it serves the enterprise and upper-mid-market segment. For email practitioners, this pattern suggests that Sailthru's infrastructure decisions, IP reputation, and authentication practices have material bearing on inbox placement for substantial organisations; senders using Sailthru and receivers accepting mail from those senders must both account for the platform's role in email delivery chains.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 6 | 0.9% |
| Top 10,000 | 77 | 12.1% |
| Top 100,000 | 211 | 33.3% |
| Top 1,000,000 | 326 | 51.4% |
| Unranked | 14 | 2.2% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 495 | 78.1% | |
| .org | 31 | 4.9% | |
| .co.uk | 21 | 3.3% | |
| .ro | 11 | 1.7% | |
| .ch | 7 | 1.1% | |
| .hu | 5 | 0.8% | |
| .net | 5 | 0.8% | |
| .tv | 4 | 0.6% | |
| .de | 4 | 0.6% | |
| .ca | 4 | 0.6% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 634 domains.
| Type | Service | Domains | Share of Sailthru users |
|---|---|---|---|
| Mailbox | Google Workspace | 310 | 48.9% |
| Mailbox | Microsoft 365 | 160 | 25.2% |
| Mailbox | Mimecast | 47 | 7.4% |
| Mailbox | Proofpoint | 46 | 7.3% |
| Mailbox | Unknown / Other | 24 | 3.8% |
| Mailbox | Self-Hosted | 7 | 1.1% |
| ESP | Amazon SES | 98 | 15.5% |
| ESP | SendGrid (Twilio) | 93 | 14.7% |
| ESP | Mandrill | 88 | 13.9% |
| ESP | Mailchimp | 74 | 11.7% |
Sailthru's prevalence in domain SPF records reflects its function as a delegated sender, handling mail delivery for organisations that maintain their own domain reputation independently. Correct SPF configuration for Sailthru-enabled senders is essential; any misconfiguration or degradation in Sailthru's IP reputation can directly affect delivery rates for downstream senders. Both senders authorising Sailthru in their SPF policy and receivers evaluating inbound mail must recognise the platform as a key node in the authentication and reputation chain for enterprise-scale email infrastructure.
See the full Sailthru data page (KPI cards, trend, sample domains) →
Sailthru is an enterprise email service provider that manages campaign delivery for large organisations; when you see it in a domain's SPF record, that domain has authorised Sailthru to send email on its behalf.
634 domains in the Tranco top-1M use Sailthru as their email service provider (ESP) as of July 13, 2026 (0.10% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Sailthru accounts for 0.10% 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.
Sailthru's largest TLD is .com (78.1% of its domains); it appears across 40 TLDs in total.