According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), 1&1 IONOS is the mailbox provider for 4,004 domains — 0.61% of 658,711 domains with MX records. Detection method: primary MX record (lowest preference).
1&1 IONOS is a German web hosting, domain registration, and mailbox provider serving a globally distributed customer base. The company offers email hosting services primarily to smaller businesses and domain owners, with significant international presence.
In the email deliverability landscape, 1&1 IONOS occupies a middle position: its footprint is concentrated in the long tail of smaller websites rather than the largest brands, and its customers are internationally distributed across many TLDs, predominantly .com domains. The provider's increasing market share has raised its relevance for senders assessing sender reputation and authentication practices across diverse, geographically scattered audiences.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 6 | 0.1% |
| Top 100,000 | 136 | 3.4% |
| Top 1,000,000 | 2,643 | 66.0% |
| Unranked | 1,219 | 30.4% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 1,714 | 42.8% | |
| .de | 828 | 20.7% | |
| .co.uk | 276 | 6.9% | |
| .org | 216 | 5.4% | |
| .net | 183 | 4.6% | |
| .fr | 168 | 4.2% | |
| .es | 117 | 2.9% | |
| .eu | 52 | 1.3% | |
| .info | 47 | 1.2% | |
| .org.uk | 36 | 0.9% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 4,004 domains.
| Type | Service | Domains | Share of 1&1 IONOS users |
|---|---|---|---|
| ESP | Mailjet (Sinch) | 130 | 3.2% |
| ESP | MailerSend | 72 | 1.8% |
| ESP | Mailgun | 71 | 1.8% |
| ESP | Brevo (ex-Sendinblue) | 63 | 1.6% |
| ESP | Amazon SES | 59 | 1.5% |
| ESP | Mandrill | 39 | 1.0% |
| ESP | Zendesk | 36 | 0.9% |
| ESP | Mailchimp | 36 | 0.9% |
| ESP | SendGrid (Twilio) | 36 | 0.9% |
| ESP | Constant Contact | 34 | 0.8% |
1&1 IONOS's concentration in the long tail and its international footprint make it a useful secondary-provider benchmark in testing matrices. Because 1&1 IONOS's customers span many countries, regions, and TLDs rather than being clustered within the major consolidated platforms, performance against 1&1 IONOS mailboxes provides signal about sender reputation and authentication stance amongst a geographically dispersed, smaller-scale recipient base. Senders can use 1&1 IONOS results as an indicator of how their email will perform beyond the top-tier providers.
See the full 1&1 IONOS data page (KPI cards, trend, sample domains) →
Yes, if your audience includes smaller businesses across international markets; 1&1 IONOS's concentration in the long tail and growing market share make it a valuable inclusion in sender testing matrices.
4,004 domains in the Tranco top-1M use 1&1 IONOS as their mailbox provider as of July 13, 2026 (0.61% of domains with MX records), according to Live Direct Marketing's daily DNS scan.
1&1 IONOS accounts for 0.61% of domains with MX records 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.
1&1 IONOS is growing — its share moved +0.10 pp over the last 30 days (as of July 13, 2026).
1&1 IONOS's largest TLD is .com (42.8% of its domains); it appears across 102 TLDs in total.