According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), k.io (workspace) is the SaaS sender for 380 domains — 0.06% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
k.io (workspace) is a SaaS email sending platform that handles outbound mail infrastructure on behalf of domains. Organisations using the service authorise it to send email by including k.io's mechanisms in their SPF (Sender Policy Framework) records, delegating a portion of their outbound mail operations to k.io's shared infrastructure.
The footprint of k.io across the internet reveals a pattern concentrated in the long tail of smaller and mid-market websites rather than the largest global brands. Its user base is internationally distributed across numerous TLDs, with a pronounced concentration in the .com namespace, and the platform is frequently observed running alongside Krystal Hosting services, particularly across the United Kingdom.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 2 | 0.5% |
| Top 100,000 | 22 | 5.8% |
| Top 1,000,000 | 267 | 70.3% |
| Unranked | 89 | 23.4% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 117 | 30.8% | |
| .co.uk | 109 | 28.7% | |
| .net | 23 | 6.1% | |
| .org.uk | 22 | 5.8% | |
| .org | 21 | 5.5% | |
| .io | 15 | 3.9% | |
| .uk | 10 | 2.6% | |
| .nl | 8 | 2.1% | |
| .dk | 8 | 2.1% | |
| .co | 3 | 0.8% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 380 domains.
| Type | Service | Domains | Share of k.io (workspace) users |
|---|---|---|---|
| Mailbox | Krystal Hosting (UK) | 151 | 39.7% |
| Mailbox | Microsoft 365 | 68 | 17.9% |
| Mailbox | Generic / unmatched (mx*.*) | 67 | 17.6% |
| Mailbox | Google Workspace | 46 | 12.1% |
| Mailbox | Self-Hosted | 11 | 2.9% |
| Mailbox | Unknown / Other | 7 | 1.8% |
As a shared email infrastructure serving many independent domains, k.io's reputation at receiving mail servers is shaped by the collective behaviour of its entire user base. When a domain authorises k.io to send mail via SPF include (typically include:k.io), that domain becomes dependent on both the infrastructure's network standing and the responsible sending practices of all other k.io users. This shared-reputation model is a fundamental characteristic of third-party email providers; understanding your infrastructure provider's user demographics, jurisdictions, and abuse mitigation practices is essential for predictable deliverability and avoiding collateral reputation damage from unrelated senders on the same platform.
See the full k.io (workspace) data page (KPI cards, trend, sample domains) →
k.io (workspace) is a third-party email service provider that the domain has authorised to send mail on its behalf. When you see <code>include:k.io</code> in an SPF record, the domain uses k.io's infrastructure for outbound email delivery, typically as a primary or supplementary mail channel.
380 domains in the Tranco top-1M use k.io (workspace) as their SaaS sender as of July 13, 2026 (0.06% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
k.io (workspace) accounts for 0.06% 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.
k.io (workspace)'s largest TLD is .com (30.8% of its domains); it appears across 41 TLDs in total.