What it reads
How many mail servers your MX records name. Two or more passes, even when one provider runs them all.
Check 14 of 54 · Email authentication
Backup mail server, explained.
Whether a second mail server can take your mail while your main one is down.
Engine 1.57.0, read 25 October 2026
Free checkAdviceReliability: Moderate
Can someone send email as you?
What the check does, and where it stops.
Why it matters
With one mail server and no backup, senders hold your mail during an outage, and a long outage makes it bounce.
What a finding looks like
What it finds is shown with a recommendation. It is advice, so it never lowers your score. If the check cannot finish, it is recorded as unknown: it carries no penalty, and it is never a pass.
Where its limits are
A resilience readout, not a security failing.
ReliabilityModerate: confirm before acting
Check 14 is one of 16 in Email authentication. See it in its row on the scanner page, beside the rest of Email authentication.
See how your domain does.
The free check includes this one and takes about 30 seconds. No account. Nothing to install.