ESP1 email service provider (ESP)
According to Live Direct Marketing's daily Tranco top-1M scan (September 17, 2026), ESP1 is the email service provider (ESP) for 129 domains — 0.02% of 635,547 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Key facts
- 129 domains in the Tranco top-1M use ESP1 (0.02% of SPF-publishing domains).
- Snapshot date: 2026-09-17 — recomputed every day.
- Strongest TLD: .com (93.0% of its domains).
- Most co-used service: Microsoft 365.
- Directory category: email service provider.
Why ESP1 appears in this category
ESP1 — Korean email service provider.
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.
What the data shows
81.4% of its domains sit outside the top 100,000 — a long-tail footprint spread across smaller sites. Its single largest TLD is .com at 93.0% of its domains — a strong concentration across 7 TLDs overall. The service most often seen alongside it is Microsoft 365 (mailbox provider), on 35.7% of its domains.
Where ESP1 sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 1 | 0.8% |
| Top 100,000 | 23 | 17.8% |
| Top 1,000,000 | 105 | 81.4% |
| Unranked | 0 | 0.0% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 120 | 93.0% | |
| .org | 2 | 1.6% | |
| .ca | 2 | 1.6% | |
| .co | 2 | 1.6% | |
| .net | 1 | 0.8% | |
| .sc | 1 | 0.8% | |
| .co.uk | 1 | 0.8% |
What ESP1 users also use
Cross-tabulated from the same daily snapshot — the other email services seen on the same 129 domains.
| Type | Service | Domains | Share of ESP1 users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 46 | 35.7% |
| Mailbox | Google Workspace | 41 | 31.8% |
| Mailbox | Mimecast | 10 | 7.8% |
| Mailbox | Proofpoint | 10 | 7.8% |
| Mailbox | Self-Hosted | 4 | 3.1% |
| Mailbox | Unknown / Other | 4 | 3.1% |
| ESP | Mailgun | 23 | 17.8% |
| ESP | Amazon SES | 22 | 17.1% |
| ESP | SendGrid (Twilio) | 21 | 16.3% |
| ESP | Zendesk | 14 | 10.9% |
See the full ESP1 data page (KPI cards, trend, sample domains) →
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Frequently asked questions
How many domains use ESP1?
129 domains in the Tranco top-1M use ESP1 as their email service provider (ESP) as of September 17, 2026 (0.02% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Is ESP1 common enough to affect email deliverability testing?
ESP1 accounts for 0.02% 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 ESP1 most?
ESP1's largest TLD is .com (93.0% of its domains); it appears across 7 TLDs in total.