this is a little manual to get POP3 working on your Milestone.
As an example i chooose german free-mail Provider GMX.
[optional]switch over to Wifi, to avoid network timeouts
 Goto Mail icon in Main Menu
 Click Options Button and select Add Account
 Select "manually Setup"
 Enter the following:
 Set TLS or SSL if neede
 Choose options on mail deleeting as liked
 Click NEXT
Now your Milestone is searching for the mailserver and tries to sign in. If successfull, it will promt you for the next steps:
 Enter SMTP Server: mail.gmx.net
 Choose Update Times
 Click NEXT and set optional name