According to Live Direct Marketing's daily Tranco top-1M scan (July 12, 2026), Q4 Inc is the email service provider (ESP) for 83 domains — 0.01% of 617,244 SPF-publishing domains. Detection method: include: mechanisms in the SPF record.
Q4 Inc is an email service provider (ESP) identified by its SPF include mechanisms across the Tranco top-1 million domain list; it operates as a delegated sender, authorised to transmit mail on behalf of the organisations that include it in their DNS authentication records.
For senders and receivers, Q4's footprint pattern—concentrated in smaller and mid-sized organisations within the .com namespace and frequently paired with Microsoft 365—signals a specialist rather than mass-market role: organisations authorising Q4 are typically channelling specific, targeted communications through it rather than general bulk mail, which affects sender reputation dynamics and the kind of scrutiny that downstream receivers apply to mail claiming Q4's authorisation.
| Tranco rank band | Domains | Share of its base |
|---|---|---|
| Top 1,000 | 2 | 2.4% |
| Top 10,000 | 2 | 2.4% |
| Top 100,000 | 20 | 24.1% |
| Top 1,000,000 | 57 | 68.7% |
| Unranked | 2 | 2.4% |
| TLD | Domains | Share | |
|---|---|---|---|
| .com | 79 | 95.2% | |
| .ca | 1 | 1.2% | |
| .net | 1 | 1.2% | |
| .xyz | 1 | 1.2% | |
| .no | 1 | 1.2% |
Cross-tabulated from the same daily snapshot — the other email services seen on the same 83 domains.
| Type | Service | Domains | Share of Q4 Inc users |
|---|---|---|---|
| Mailbox | Microsoft 365 | 30 | 36.1% |
| Mailbox | Proofpoint | 12 | 14.5% |
| Mailbox | Google Workspace | 11 | 13.3% |
| Mailbox | Mimecast | 9 | 10.8% |
| Mailbox | Cisco IronPort | 5 | 6.0% |
| Mailbox | Self-Hosted | 4 | 4.8% |
| ESP | Salesforce | 22 | 26.5% |
| ESP | HubSpot | 13 | 15.7% |
| ESP | Mimecast | 12 | 14.5% |
| ESP | Amazon SES | 12 | 14.5% |
Q4's consistent presence in SPF records of the long-tail middle market, rather than the largest brands, reflects its position as a specialist ESP; this distribution matters for receivers and senders alike because Q4's sending reputation is built on a narrower, more defined use case than consumer-focused ESPs, and its authorisation in an SPF record often signals that a domain's mail architecture includes a targeted, non-bulk communication channel.
See the full Q4 Inc data page (KPI cards, trend, sample domains) →
It means your domain (or a department within your organisation) has authorised Q4 to send email on your behalf, typically for a specific communication workflow; if you did not explicitly set this, a team member, agency, or legacy service configuration may have added it.
83 domains in the Tranco top-1M use Q4 Inc as their email service provider (ESP) as of July 12, 2026 (0.01% of SPF-publishing domains), according to Live Direct Marketing's daily DNS scan.
Q4 Inc accounts for 0.01% 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.
Q4 Inc's largest TLD is .com (95.2% of its domains); it appears across 5 TLDs in total.