No MX on a sending domain
Replies bounce and some providers treat the domain as suspicious.
Tools · 30 seconds
MX lookup
See which mail servers receive email for a domain, in priority order, and which email provider runs them.
Runs in your browser · public DNS records only · nothing stored
What MX records do
MX (mail exchange) records tell the world which servers receive email for a domain. Each has a priority number: lower numbers are tried first, higher ones are backups.
For sales teams an MX lookup answers two questions: which email provider a prospect uses (Google, Microsoft or a security gateway), and whether your own sending domain can receive replies.
What the provider tells you
- Google WorkspaceMX ends in google.com or googlemail.com.
- Microsoft 365MX ends in mail.protection.outlook.com.
- Security gatewayProofpoint (pphosted.com) or Mimecast: stricter filtering, so plain text and few links matter more.
- NoneReplies bounce. Never send cold email from a domain without MX.
Reading MX records
| Field | Example | Meaning |
|---|---|---|
Priority | 1, 5, 10 | Lower is tried first. Equal numbers share the load. |
Mail server | aspmx.l.google.com | The host that accepts email. Must be a name, not an IP or CNAME. |
Null MX | 0 . | The domain says it never receives email. |
Common MX problems
MX pointing to an IP address
Not allowed by the standard. Use a host name.
Old provider still listed
After a move, delete the old MX records or some email goes to the old system.
MX pointing to a CNAME
Not allowed by the standard; some servers refuse it.
Gmail and Yahoo sender rules
What inbox providers require since February 2024
Bulk senders send about 5,000 or more emails a day to Gmail. Cold email teams reach that quickly across mailboxes, so treat the bulk rules as the standard.
Source: Google email sender guidelines
| Rule | Who | Requirement |
|---|---|---|
| SPF or DKIM | All senders | Required |
| SPF and DKIM | Bulk senders | Required |
| DMARC, p=none or stronger | Bulk senders | Required |
| From domain aligned with SPF or DKIM | Bulk senders | Required |
| One-click unsubscribe | Bulk senders, marketing email | Required |
| Spam complaint rate | All senders | Below 0.3 percent |
Questions people ask
How do I find a domain’s MX records?
Enter the domain above. The lookup lists every MX record in priority order and names the email provider where it recognises one.
What does MX priority mean?
Servers with the lowest number are tried first. If they do not answer, the next number is tried. Equal numbers share the email.
Does a cold email domain need MX records?
Yes. Without MX, replies bounce and inbox providers trust the domain less. Point it at the same mailbox provider you send from.
Can I see which provider a prospect uses?
Yes, MX records are public. Knowing a company uses Microsoft 365 or a security gateway helps you keep emails plain, short and link-light.
Is my domain stored?
No. The check runs in your browser. Your browser asks Cloudflare’s public DNS service (or Google’s, as a fallback) for the domain’s public records, the same records every mail server reads. RevOps Lab does not receive or store the domain or the result.