SupportBox (CZ) SaaS sender
According to Live Direct Marketing's daily Tranco top-1M scan (September 14, 2026), SupportBox (CZ) is the SaaS sender for 301 domains — 0.05% of 637,677 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Key facts
- 301 domains in the Tranco top-1M use SupportBox (CZ) (0.05% of SPF-publishing domains).
- Snapshot date: 2026-09-14 — recomputed every day.
- Strongest TLD: .cz (58.8% of its domains).
- Most co-used service: Google Workspace.
- Directory category: SaaS sender.
Why SupportBox (CZ) appears in this category
Czech helpdesk SaaS for SMB customer support.
We classify it as a SaaS sender from include: mechanisms in the SPF record matching a maintained provider rule. This is infrastructure attribution from public DNS, not evidence of a direct contract or exclusive use.
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.
Where SupportBox (CZ) sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 1 | 0.3% |
| Top 100,000 | 15 | 5.0% |
| Top 1,000,000 | 284 | 94.4% |
| Unranked | 1 | 0.3% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .cz | 177 | 58.8% | |
| .sk | 39 | 13.0% | |
| .hu | 22 | 7.3% | |
| .com | 15 | 5.0% | |
| .de | 10 | 3.3% | |
| .pl | 7 | 2.3% | |
| .ro | 6 | 2.0% | |
| .eu | 5 | 1.7% | |
| .com.ua | 3 | 1.0% | |
| .si | 2 | 0.7% |
What SupportBox (CZ) users also use
Cross-tabulated from the same daily snapshot — the other email services seen on the same 301 domains.
| Type | Service | Domains | Share of SupportBox (CZ) users |
|---|---|---|---|
| Mailbox | Google Workspace | 69 | 22.9% |
| Mailbox | Microsoft 365 | 42 | 14.0% |
| Mailbox | Shoptet (CZ) | 40 | 13.3% |
| Mailbox | Unknown / Other | 33 | 11.0% |
| Mailbox | Seznam.cz (Czech) | 21 | 7.0% |
| Mailbox | Self-Hosted | 20 | 6.6% |
SPF delegation and recognition in the Czech email stack
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) →
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Frequently asked questions
What is SupportBox (CZ) in the context of email deliverability?
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.
How many domains use SupportBox (CZ)?
301 domains in the Tranco top-1M use SupportBox (CZ) as their SaaS sender as of September 14, 2026 (0.05% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Is SupportBox (CZ) common enough to affect email deliverability testing?
SupportBox (CZ) accounts for 0.05% 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.
Which countries or TLDs use SupportBox (CZ) most?
SupportBox (CZ)'s largest TLD is .cz (58.8% of its domains); it appears across 23 TLDs in total.