According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Retarus (DE gateway) is the email service provider (ESP) for 189 domains — 0.03% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Retarus is a German email service provider specialising in managed SMTP gateways and message relay infrastructure. The company operates email delivery platforms serving organisations across Europe and internationally, providing services including message relay, security filtering, and archiving through its gateway network.
Retarus appears frequently in SPF authentication mechanisms across the web, indicating that many organisations have delegated their outbound mail relay to Retarus's infrastructure. The provider's footprint concentrates in the mid-market and small-to-medium business segment rather than amongst the largest global enterprises, with particularly strong adoption across German-language domains (.de) and other European top-level domains, reflecting its primary geographic market.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 3 | 1.6% |
| Top 100,000 | 28 | 14.8% |
| Top 1,000,000 | 151 | 79.9% |
| Unranked | 7 | 3.7% |
| TLD | Domains | Share | |
|---|---|---|---|
| .de | 75 | 39.7% | |
| .com | 58 | 30.7% | |
| .fr | 10 | 5.3% | |
| .ch | 8 | 4.2% | |
| .at | 6 | 3.2% | |
| .it | 5 | 2.6% | |
| .es | 4 | 2.1% | |
| .nl | 3 | 1.6% | |
| .cz | 2 | 1.1% | |
| .eu | 2 | 1.1% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 189 domains.
| Type | Service | Domains | Share of Retarus (DE gateway) users |
|---|---|---|---|
| Mailbox | Retarus | 83 | 43.9% |
| Mailbox | Microsoft 365 | 67 | 35.4% |
| Mailbox | Self-Hosted | 11 | 5.8% |
| Mailbox | Proofpoint | 6 | 3.2% |
| Mailbox | Mimecast | 5 | 2.6% |
| Mailbox | Unknown / Other | 4 | 2.1% |
| ESP | IP Made (CDP) | 32 | 16.9% |
| ESP | Mailgun | 19 | 10.1% |
| ESP | Mailchimp | 12 | 6.3% |
| ESP | Salesforce | 12 | 6.3% |
Because Retarus operates as a shared gateway platform for many customers, sender reputation at Retarus's IP addresses is pooled across the relay's entire customer base. Mail receivers that track IP reputation will associate inbound traffic from Retarus relays with the aggregate sending behaviour of all Retarus customers, not just an individual sender. This means that a deliverability issue affecting one Retarus customer—such as complaint spikes or sending to invalid addresses—can degrade message acceptance rates across other customers using the same relay addresses.
See the full Retarus (DE gateway) data page (KPI cards, trend, sample domains) →
Retarus is a German email gateway and managed relay provider that handles outbound SMTP traffic for many mid-market organisations. You will see Retarus's SPF include mechanisms in domains where the organisation has delegated their mail delivery to Retarus's infrastructure.
189 domains in the Tranco top-1M use Retarus (DE gateway) as their email service provider (ESP) as of July 13, 2026 (0.03% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Retarus (DE gateway) accounts for 0.03% 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.
Retarus (DE gateway)'s largest TLD is .de (39.7% of its domains); it appears across 24 TLDs in total.