According to Live Direct Marketing's daily Tranco top-1M scan (July 13, 2026), Rule is the email service provider (ESP) for 152 domains — 0.02% of 617,702 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Rule is an email service provider identified through SPF include mechanisms in domain configurations. It occupies the long tail of smaller organisations rather than the largest global brands, with particular prevalence in Swedish (.se) domains where it frequently co-deploys with Microsoft 365 infrastructure.
When Rule appears in a sender's SPF record or your own email routing, it represents a deliberate infrastructure choice. Understanding Rule's reputation profile and how it integrates with Microsoft 365—and how filters may treat traffic authorised by Rule's netblocks—is relevant for both outbound deliverability and inbound filtering decisions, particularly for organisations serving Scandinavian markets.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 2 | 1.3% |
| Top 100,000 | 20 | 13.2% |
| Top 1,000,000 | 112 | 73.7% |
| Unranked | 18 | 11.8% |
| TLD | Domains | Share | |
|---|---|---|---|
| .se | 84 | 55.3% | |
| .com | 35 | 23.0% | |
| .de | 13 | 8.6% | |
| .fi | 5 | 3.3% | |
| .nu | 4 | 2.6% | |
| .dk | 3 | 2.0% | |
| .no | 2 | 1.3% | |
| .nl | 2 | 1.3% | |
| .org | 1 | 0.7% | |
| .net | 1 | 0.7% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 152 domains.
| Type | Service | Domains | Share of Rule users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 94 | 61.8% |
| Mailbox | Google Workspace | 31 | 20.4% |
| Mailbox | Unknown / Other | 12 | 7.9% |
| Mailbox | Generic / unmatched (mx*.*) | 5 | 3.3% |
| Mailbox | Hornetsecurity | 3 | 2.0% |
| Mailbox | Mimecast | 1 | 0.7% |
| ESP | Zendesk | 29 | 19.1% |
| ESP | Amazon SES | 27 | 17.8% |
| ESP | Mandrill | 27 | 17.8% |
| ESP | SendGrid (Twilio) | 22 | 14.5% |
Rule's concentration in Swedish and Nordic markets, frequently deployed alongside Microsoft 365, creates a distinct reputation profile separate from global ESPs. Organisations sending to Scandinavian recipients or using Rule within those markets should monitor whether regional ISP filters, corporate gateways, or anti-spam systems apply differentiated policies to SPF-authorised traffic from Rule's authorised send netblocks, since the combination of smaller-brand adoption and geographic clustering may affect filtering behaviour differently than major international ESPs.
See the full Rule data page (KPI cards, trend, sample domains) →
Rule is a long-tail email service provider with strongest adoption in Swedish and Scandinavian organisations; it is not a primary filtering concern for global senders. If your recipient base includes Nordic or Swedish enterprises, checking Rule's sender reputation and testing against regional filtering policies is worthwhile.
152 domains in the Tranco top-1M use Rule as their email service provider (ESP) as of July 13, 2026 (0.02% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Rule accounts for 0.02% 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.
Rule's largest TLD is .se (55.3% of its domains); it appears across 12 TLDs in total.