What is a recommended TTL for MX records?

If you're planning to migrate your mail server, your TTL setting is one of the first things to think about. Get it wrong and you could be waiting hours for the switch to take effect while emails bounce around in limbo.

Here's the short version: drop your TTL before the migration, do the work, then raise it back up again once things are stable.

Normal operation

For day-to-day use, a TTL between 3600 and 14400 seconds (1 to 4 hours) is perfectly fine. It balances caching efficiency with a reasonable update window. Most setups sit at 3600 seconds and never need to think about it again.

Before a migration

Lower your TTL to 300 to 600 seconds (5 to 10 minutes) at least 24 to 48 hours before the planned change. This is the important part. DNS resolvers around the world will be caching your current record, so you need to give them time to flush that cache and start picking up the shorter TTL. If you wait until the day of your migration to lower the TTL, you've missed the window. (Think of it like telling people your new address before you actually move.)

A shorter TTL means that once you flip to your new mail server, the change propagates much faster. That's especially useful if something goes sideways and you need to roll back quickly.

After migration

Once your new mail server is running cleanly for a day or two, raise the TTL back to 3600 seconds or higher. A low TTL means resolvers are querying your DNS constantly, which adds unnecessary load. Once you're confident the setup is solid, there's no reason to keep it short.

So for your specific situation: you're currently at 14400 seconds. Lower it to 300 or 600 seconds now, wait 24 to 48 hours, then do your migration. Raise it back to 3600 (or 14400 if you prefer) once you've confirmed everything is working.

Curious how TTL fits into the bigger picture of how DNS caching works? That's worth a quick read before you make the change. And if you're also updating your authentication records at the same time, the same pre-migration TTL logic applies there too.