[support] changing host: dealing with mails

Hello,

One of my web sites is changing host. I have prepared the Drupal files, and used /etc/hosts to test the Drupal site at its new location. Now, I only need to shut down the site, make a last sql dump, import it and then, lastly, change the DNS.

But it only now occurred to me that migrating a web server is only half of changing hosts.

What about mails?

What is a good procedure to migrate all the mails on the server, and also to make sure that no mail is lost during the DNS change (during the propagation of the new DNS)?

I have not found a page on the web about a best practice about changing hosts, what data to migrate, what not, and how to be prepared to avoid troubles.

Any hints?

Thanks.

Augustin.