Mail still routing to the old server after migration?

[LiamMotorCommerce]

Hi All,

I've recently started migrating our websites from one of our Linux servers to a new one hosted with a different company. The migration went well with no errors and we've been managing to get these websites up and running with no problems. The problem that we do have however is the customer emails. Many of our customers are able to send email fine but they are unable to receive (and receive no error messages). Upon investigation I have found that somehow the email is still being routes to the old server (I found the mail was going to the old server by looking in /var/qmail/mailnames/<domain>/<email>/Maildir/cur). The DNS settings are definitely correct and are pointing to the new server, as well as the nameservers which have also been changed.

I've run a test on mxtoolbox.com and even this is showing the correct settings. Can anyone help me with this?

Thanks,

Liam

 

[Faris Raouf]

DNS records are often cached. Indeed, before a change of IP, it is usually sensible to change the TTL to something like 4 or 5 minutes instead of whatever it might be by default, which could be several days.

Even with a short TTL, some email may still get sent to your old IPs. There are a number of ways to get around this.
Personally I firewall the old machine before starting a Migration. Yes, email will be down for X hours, but that email won't (or should not) get lost because sending servers will retry sending for (usually) at least 24 hours before giving up.

There is an application that uses IMAP to copy messages from one server to another, but you can possibly more easily use rsync between the two machines to do so (making sure you do so in a way that does not overwrite anything on the new server).

Faris.