According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), CSOF (DE) is the mailbox provider for 491 domains — 0.07% of 658,711 domains with MX records. Detection method: primary MX record (lowest preference).
CSOF (DE) is a mailbox provider—a mail-hosting service that manages inbound and outbound mail infrastructure. It serves a global customer base with a slight US skew, concentrated predominantly in the .com namespace.
Because CSOF (DE) sits in the long tail of smaller websites rather than among the largest brands, mainstream senders encounter it less frequently; however, it remains relevant for smaller campaigns and niche verticals. Its frequent pairing with Mailspike, a third-party mail reputation service, suggests customers often layer additional email management atop base hosting, which can affect how authentication and feedback signals flow.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 0 | 0.0% |
| Top 100,000 | 26 | 5.3% |
| Top 1,000,000 | 398 | 81.1% |
| Unranked | 67 | 13.6% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 225 | 45.8% | |
| .net | 58 | 11.8% | |
| .biz | 27 | 5.5% | |
| .one | 12 | 2.4% | |
| .fr | 11 | 2.2% | |
| .in | 9 | 1.8% | |
| .xyz | 8 | 1.6% | |
| .club | 8 | 1.6% | |
| .ru | 8 | 1.6% | |
| .co | 7 | 1.4% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 491 domains.
| Type | Service | Domains | Share of CSOF (DE) users |
|---|---|---|---|
| ESP | Mailspike | 482 | 98.2% |
When CSOF (DE) is deployed alongside Mailspike, responsibility for SPF, DKIM, and DMARC records—and for bounce handling and complaint feedback—may be split between the two services. Senders should verify which platform owns DNS configuration and which receives feedback loops to avoid conflicts or missed signals during troubleshooting.
See the full CSOF (DE) data page (KPI cards, trend, sample domains) →
Yes, if your audience includes smaller .com sites or niches where CSOF (DE) is deployed. Since it occupies the long tail rather than mainstream carriers, prioritise larger providers first unless you have direct evidence your actual recipients use it.
491 domains in the Tranco top-1M use CSOF (DE) as their mailbox provider as of July 13, 2026 (0.07% of domains with MX records), according to Live Direct Marketing's daily DNS scan.
CSOF (DE) accounts for 0.07% 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.
CSOF (DE)'s largest TLD is .com (45.8% of its domains); it appears across 67 TLDs in total.