Skip to content
DomainGrade

What we checkEmailEM-09

Mail servers resolve

Every MX hostname should resolve to a public address that can actually accept mail.

Area
Email
Check
EM-09
Included
Free in every scan

What we check

We resolve each MX hostname and check it has an address, and that the address is a public one.

Why it matters

An MX that does not resolve means mail to your domain bounces. It is the sort of thing that happens after a migration and is discovered by a customer rather than by you.

An MX pointing at a private address is worse in a subtler way: it works from inside your network and fails from everywhere else.

It is also the finding most often introduced by a migration that went fine. The MX records point at the old provider, the old provider stops answering some weeks later, and nothing in your own mailbox changes to tell you — because your outgoing mail was never the part that broke.

How to fix it

  1. 1

    Check each MX hostname resolves from outside your network.

  2. 2

    Remove records for servers that no longer exist.

Common questions

My MX resolves fine for me.
Check from outside your own network. A hostname that resolves internally to a private address is the most common cause of this finding.
Can an MX record point at an IP address?
No — MX records must name a hostname. An IP there is invalid and receivers will not use it.
Does this mean my mail is down?
If every MX fails to resolve, yes. If one of several fails, mail still flows through the others, but you have lost the redundancy you thought you had.

See how your domain does on this check.

All 34 checks, a grade, and the exact fix for anything that isn’t right — in about twenty seconds, no signup.

Other email checks