An MX (Mail Exchanger) record is the DNS entry that tells other mail servers where to deliver email for your domain. Without one pointing at your provider, mail to your address has nowhere to go.
How it works
A sending server that has mail for you@yourdomain.com looks up the MX records of yourdomain.com and connects to the host they name. Each record has a priority number; lower is preferred. Records with higher numbers are fallbacks, tried when the preferred host does not answer. Mail routing via MX is specified in RFC 5321.
Changing providers
Switching your MX records is the moment your mail starts arriving at the new provider — and the moment it stops arriving at the old one. DNS changes take effect as caches expire, so for a while some senders reach the new server and some the old. That overlap is why migration guides tell you to keep the old account open for a few weeks rather than closing it the day you switch.
MX records must point at a hostname, not an IP address, and the hostname must not itself be an alias (CNAME).
How to check yours
dig +short MX yourdomain.comMX at Mailotte
mailotte.com's primary MX record points at mail.mailotte.com at priority 10. When you connect your own domain, Mailotte gives you an MX record pointing at the same host.
Questions
What does the MX priority number mean?
Lower numbers are tried first. A record at 20 is only used when the one at 10 does not respond.
How long does an MX change take?
It depends on the TTL of your old record — commonly an hour, sometimes a day. Expect a window in which mail arrives at both old and new providers.
Can an MX record point at an IP address?
No. It has to name a hostname, and that hostname must have its own A or AAAA record rather than being a CNAME.
Related terms
- SPF — Sender Policy Framework
- MTA-STS — SMTP MTA Strict Transport Security
- Catch-all address — Catch-all mailbox
- All terms