[Mailman-Users] Setup problem

Hello,

My problem is quite simple:

our mail server is behind a dial up connection, the mail is stocked on

our ISP's mail server until we open a connection. The mail is then delivered to an IMAP server.

I would like to divert mail for mailman lists to another machine on the LAN. Does some sendmail/IMAP guru have the secret recipie to do this?

TIA

Tony Grant