Rule email service provider (ESP)
According to Live Direct Marketing's daily Tranco top-1M scan (September 19, 2026), Rule is the email service provider (ESP) for 146 domains — 0.02% of 642,799 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Key facts
- 146 domains in the Tranco top-1M use Rule (0.02% of SPF-publishing domains).
- Snapshot date: 2026-09-19 — recomputed every day.
- Strongest TLD: .se (55.5% of its domains).
- Most co-used service: Microsoft 365.
- Directory category: email service provider.
Why Rule appears in this category
Rule — Swedish marketing automation.
We classify it as a email service provider 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.
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.
Where Rule sits in the Tranco ranking
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 0 | 0.0% |
| Top 10,000 | 2 | 1.4% |
| Top 100,000 | 18 | 12.3% |
| Top 1,000,000 | 124 | 84.9% |
| Unranked | 2 | 1.4% |
Top-level domain split
| TLD | Domains | Share | |
|---|---|---|---|
| .se | 81 | 55.5% | |
| .com | 34 | 23.3% | |
| .de | 11 | 7.5% | |
| .dk | 4 | 2.7% | |
| .fi | 4 | 2.7% | |
| .no | 3 | 2.1% | |
| .nu | 3 | 2.1% | |
| .org | 2 | 1.4% | |
| .net | 1 | 0.7% | |
| .nl | 1 | 0.7% |
What Rule users also use
Cross-tabulated from the same daily snapshot — the other email services seen on the same 146 domains.
| Type | Service | Domains | Share of Rule users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 92 | 63.0% |
| Mailbox | Google Workspace | 30 | 20.5% |
| Mailbox | Unknown / Other | 9 | 6.2% |
| Mailbox | Generic / unmatched (mx*.*) | 5 | 3.4% |
| Mailbox | Hornetsecurity | 2 | 1.4% |
| Mailbox | Loopia (SE) | 2 | 1.4% |
| ESP | Amazon SES | 27 | 18.5% |
| ESP | Zendesk | 27 | 18.5% |
| ESP | Mandrill | 25 | 17.1% |
| ESP | SendGrid (Twilio) | 21 | 14.4% |
Rule's geographic and technical context in Scandinavian email infrastructure
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) →
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Frequently asked questions
Is Rule a major deliverability concern for email senders?
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.
How many domains use Rule?
146 domains in the Tranco top-1M use Rule as their email service provider (ESP) as of September 19, 2026 (0.02% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Is Rule common enough to affect email deliverability testing?
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.
Which countries or TLDs use Rule most?
Rule's largest TLD is .se (55.5% of its domains); it appears across 12 TLDs in total.