Why It Matters
No MX record, no email. It's that simple. If your domain's MX records are missing or misconfigured, emails sent to you will bounce. And if you're setting up a custom domain for sending, you'll need MX records pointing to the right infrastructure. They're one of the first things to check when email stops working.
How It Works
MX records live in your domain's DNS zone file. Each record has two parts: a priority value and a mail server hostname. Lower priority numbers get tried first. For example:
10 mail1.example.com(primary)20 mail2.example.com(backup)
When a sending server wants to deliver mail to you@example.com, it queries DNS for the MX records of example.com, picks the lowest-priority server, and attempts delivery via SMTP. If that server is down, it falls back to the next one.
Quick Tips
- Always set at least two MX records with different priorities for redundancy
- Double-check that the hostnames in your MX records have valid A records -- an MX pointing to a non-existent server means lost mail
- After changing MX records, allow 24-48 hours for DNS propagation before expecting everything to work