Email Provider Lookup
How to identify which mail service a domain uses by reading its DNS records.
What Is Email Provider Lookup?
Email provider lookup is the process of determining which mail service handles email for a given domain. Every domain that can receive email has MX records in its DNS configuration. These records point to the mail servers of the provider — whether that is Google Workspace, Microsoft 365, Zoho Mail, ProtonMail, or another service.
How Provider Identification Works
The Email Provider Filter identifies providers through a three-step DNS analysis:
- SPF record check — The Sender Policy Framework (SPF) TXT record lists which servers are authorized to send email for the domain. Providers include their own SPF mechanisms, such as
_spf.google.comorspf.protection.outlook.com. SPF is checked first because it often reveals the true provider even when a filtering service owns the MX records. - MX record check — Mail Exchange records specify where email should be delivered. Each provider has characteristic MX hostnames (e.g.,
aspmx.l.google.comfor Google,*.protection.outlook.comfor Microsoft). - Verification token check — Some providers embed verification tokens in TXT records (e.g.,
ms=ms...for Microsoft), which serve as a secondary identification method.
Providers the Tool Can Identify
The Email Provider Filter recognizes 26+ mail providers, including:
- Google (Gmail / Google Workspace)
- Microsoft (Outlook / Microsoft 365)
- Yahoo
- Apple (iCloud)
- Zoho Mail
- ProtonMail
- Amazon SES
- Mailgun
- SendGrid
- Postmark
- Fastmail
- Tutanota
- Yandex
- GoDaddy
- Rackspace
- Namecheap
- Cloudflare
- Hostinger
- Bluehost
- SiteGround
- DreamHost
- GMX
- Mimecast
- Proofpoint
- Barracuda
Why SPF Matters for Provider Lookup
Many organizations use third-party filtering services like Mimecast, Proofpoint, or Barracuda to screen incoming email. These services become the MX target, which means a simple MX lookup would identify the filter, not the actual mail provider. By checking SPF records first, the tool can often identify the underlying provider — for example, a domain might have Mimecast MX records but an SPF include for spf.protection.outlook.com, revealing that Microsoft 365 is the true mail platform.
Use Cases for Provider Lookup
- Sales intelligence — Knowing a prospect's email platform helps tailor product pitches and integration suggestions.
- IT audits — Inventorying mail providers across many domains to ensure compliance with organizational standards.
- Migration planning — Understanding the current provider landscape before a consolidation or migration project.
- Security analysis — Detecting unexpected provider changes that might indicate domain takeover or misconfiguration.
Related Resources
- Email Domain Checker — what DNS records reveal about a domain
- MX Record Checker — how MX records route email
- How to Find the Email Provider Behind a Domain
- What DNS Records Tell You About an Email Domain