T-Online mailbox provider
According to Live Direct Marketing's daily Tranco top-1M scan (September 14, 2026), T-Online is the mailbox provider for 15 domains — 0.00% of 674,487 domains with MX records. Detection method: primary MX record (lowest preference).
Key facts
- 15 domains in the Tranco top-1M use T-Online (0.00% of domains with MX records).
- Snapshot date: 2026-09-14 — recomputed every day.
- Strongest TLD: .de (73.3% of its domains).
- Region skew: Germany.
- Directory category: mailbox provider.
Why T-Online appears in this category
Telekom Germany consumer ISP mail.
We classify it as a mailbox provider from primary MX record (lowest preference) matching a maintained provider rule. This is infrastructure attribution from public DNS, not evidence of a direct contract or exclusive use.
T-Online is the email and web hosting service operated by Deutsche Telekom, Germany's largest telecommunications provider. It serves as a primary mailbox platform for users across the German-speaking regions and is a foundational element of the German internet infrastructure.
T-Online's prevalence in the Tranco top-1M dataset skews heavily towards high-traffic, enterprise, and well-known sites concentrated in the .de namespace. For senders and organisations managing email to German recipients or hosting on German infrastructure, T-Online's filtering and acceptance policies represent a critical touchpoint; its prominence means that deliverability failures to T-Online will likely affect a significant portion of any German-focused mail stream.
Where T-Online sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 1 | 6.7% |
| Top 10,000 | 1 | 6.7% |
| Top 100,000 | 1 | 6.7% |
| Top 1,000,000 | 11 | 73.3% |
| Unranked | 1 | 6.7% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .de | 11 | 73.3% | |
| .eu | 1 | 6.7% | |
| .net | 1 | 6.7% | |
| .com | 1 | 6.7% | |
| .org | 1 | 6.7% |
T-Online's role in German market mail flow
Because T-Online appears as the primary MX for many high-traffic and established German sites—rather than just consumer domains—organisations sending into the German market must account for T-Online's acceptance criteria as a distinct segment within their deliverability strategy. Testing and monitoring T-Online delivery separately from other European providers is essential for verifying that mail from your infrastructure reaches German recipients reliably, particularly when those recipients are affiliated with enterprise or well-known domains.
See the full T-Online data page (KPI cards, trend, sample domains) →
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Frequently asked questions
Should I test email deliverability specifically to T-Online?
Yes, if you send to German recipients or domains in the .de namespace; T-Online's concentration among high-traffic and enterprise sites in Germany makes it a primary barometer for German mail deliverability.
How many domains use T-Online?
15 domains in the Tranco top-1M use T-Online as their mailbox provider as of September 14, 2026 (0.00% of domains with MX records), according to Live Direct Marketing's daily DNS scan.
Is T-Online common enough to affect email deliverability testing?
T-Online accounts for 0.00% 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.
Which countries or TLDs use T-Online most?
T-Online's largest TLD is .de (73.3% of its domains); it appears across 5 TLDs in total.