> Does exist some way to use POP3Client behind a proxy (as with 
> HTTPSocket>>useProxyServerNamed)?

I use ssh-forwarding for sending mail. This should work for POP, too.

For SMTP, I do:
     sudo ssh user_at_some.machine.org  -L 25:mail.domain.ch:25

where "some.machine" is a computer that has access to the mail server 
(e.g. it's on the right side of the firewall).

Then just use "localhost" in squeak as your SMTP. For POP, you just 
need to change the port (110, I think).

The good thing with this is that everyting is transmitted encrypted. So 
no problems with transmitting passwords.

     Marcus