According to Live Direct Marketing's daily Tranco top-1M scan (July 12, 2026), SupportBox (CZ) is the SaaS sender for 266 domains — 0.04% of 617,244 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
SupportBox (CZ) is a Czech-based SaaS platform that domain holders use to delegate email sending. It appears in SPF records of the domains using it, authorising the platform to send mail on their behalf.
The service concentrates among smaller .cz-hosted websites rather than major brands, often appearing alongside Google Workspace. For senders testing mail delivery and email receivers evaluating infrastructure, recognising SupportBox (CZ) as a standard Czech email service is useful context: it explains why certain domains delegate mail to a third party, and helps distinguish between sender-level reputation issues and platform-level infrastructure decisions.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 1 | 0.4% |
| Top 100,000 | 13 | 4.9% |
| Top 1,000,000 | 230 | 86.5% |
| Unranked | 22 | 8.3% |
| TLD | Domains | Share | |
|---|---|---|---|
| .cz | 158 | 59.4% | |
| .sk | 32 | 12.0% | |
| .hu | 18 | 6.8% | |
| .com | 14 | 5.3% | |
| .de | 8 | 3.0% | |
| .pl | 8 | 3.0% | |
| .eu | 5 | 1.9% | |
| .ro | 4 | 1.5% | |
| .si | 2 | 0.8% | |
| .hr | 2 | 0.8% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 266 domains.
| Type | Service | Domains | Share of SupportBox (CZ) users |
|---|---|---|---|
| Mailbox | Google Workspace | 55 | 20.7% |
| Mailbox | Microsoft 365 | 51 | 19.2% |
| Mailbox | Shoptet (CZ) | 35 | 13.2% |
| Mailbox | Unknown / Other | 27 | 10.2% |
| Mailbox | Self-Hosted | 17 | 6.4% |
| Mailbox | Seznam.cz (Czech) | 15 | 5.6% |
SupportBox (CZ) appears in SPF records as an authorised sending platform, typically added alongside other services like Google Workspace to form a domain's delegated mail chain. For administrators managing Czech domain infrastructure, recognising SupportBox (CZ) in an SPF record is routine; for senders and filters evaluating mail from .cz domains, understanding its role in the delegated stack helps distinguish between issues rooted in the domain itself versus those caused by platform-level problems. Because it concentrates among smaller sites rather than the largest brands, senders may encounter it irregularly unless they focus testing on regional or niche sectors within the Czech market.
See the full SupportBox (CZ) data page (KPI cards, trend, sample domains) →
SupportBox (CZ) is a Czech email-sending platform that domain holders use to delegate outbound mail, appearing in SPF records as an authorised third-party service. It is most common among smaller .cz websites and is typically used alongside Google Workspace.
266 domains in the Tranco top-1M use SupportBox (CZ) as their SaaS sender as of July 12, 2026 (0.04% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
SupportBox (CZ) accounts for 0.04% 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.
SupportBox (CZ)'s largest TLD is .cz (59.4% of its domains); it appears across 23 TLDs in total.