Sailthru email service provider (ESP)
According to Live Direct Marketing's daily Tranco top-1M scan (September 24, 2026), Sailthru is the email service provider (ESP) for 620 domains — 0.10% of 637,420 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Key facts
- 620 domains in the Tranco top-1M use Sailthru (0.10% of SPF-publishing domains).
- Snapshot date: 2026-09-24 — recomputed every day.
- Strongest TLD: .com (78.9% of its domains).
- Most co-used service: Google Workspace.
- Directory category: email service provider.
Why Sailthru appears in this category
Marigold Sailthru — publisher-focused personalisation ESP.
We classify it as a email service provider from include: mechanisms in the SPF record matching a maintained provider rule. This is infrastructure attribution from public DNS, not evidence of a direct contract or exclusive use.
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.
Where Sailthru sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 7 | 1.1% |
| Top 10,000 | 68 | 11.0% |
| Top 100,000 | 208 | 33.5% |
| Top 1,000,000 | 336 | 54.2% |
| Unranked | 1 | 0.2% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 489 | 78.9% | |
| .org | 31 | 5.0% | |
| .co.uk | 21 | 3.4% | |
| .ro | 12 | 1.9% | |
| .ch | 7 | 1.1% | |
| .hu | 5 | 0.8% | |
| .net | 4 | 0.6% | |
| .ca | 4 | 0.6% | |
| .tv | 4 | 0.6% | |
| .fm | 3 | 0.5% |
What Sailthru users also use
Cross-tabulated from the same daily snapshot — the other email services seen on the same 620 domains.
| Type | Service | Domains | Share of Sailthru users |
|---|---|---|---|
| Mailbox | Google Workspace | 296 | 47.7% |
| Mailbox | Microsoft 365 | 163 | 26.3% |
| Mailbox | Mimecast | 51 | 8.2% |
| Mailbox | Proofpoint | 42 | 6.8% |
| Mailbox | Unknown / Other | 20 | 3.2% |
| Mailbox | Self-Hosted | 8 | 1.3% |
| ESP | Amazon SES | 96 | 15.5% |
| ESP | Mandrill | 91 | 14.7% |
| ESP | SendGrid (Twilio) | 88 | 14.2% |
| ESP | Mailchimp | 73 | 11.8% |
SPF delegation and sender authorisation
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) →
Run a free inbox-placement test across Gmail, Outlook, Yahoo and more — see exactly where your mail lands and why.
Frequently asked questions
What is Sailthru and why do I see it in SPF records?
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.
How many domains use Sailthru?
620 domains in the Tranco top-1M use Sailthru as their email service provider (ESP) as of September 24, 2026 (0.10% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Is Sailthru common enough to affect email deliverability testing?
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.
Which countries or TLDs use Sailthru most?
Sailthru's largest TLD is .com (78.9% of its domains); it appears across 37 TLDs in total.