Weird imap problems

[david at thekramers.net (David Kramer)]

John Abreau wrote:
> I'm running Courier IMAP, and I ran into a problem today that's 
> driving me nuts. I was fixing a problem with our openldap server 
> earlier today, and after resolving that, I started to check for other 
> problems that might have come up as a result. 
> 
> When I checked our squirrelmail service, it wouldn't connect to imap; 
> I get the message 
> 
>     ERROR : Connection dropped by imap-server.
> 
> It turns out when I try telnet'ing to port 143 of the imap server from 
> the server that squirrelmail is on, it disconnects immediately, and
> nothing is appearing in the logs on either server related to imap. 
> But from my other servers and desktops, telnet'ing to port 143 of the 
> imap server works just fine, and mail clients are working okay. 
> 
> Any ideas of what might cause this? The server running squirrelmail 
> is Red Hat Enterprise Linux ES release 3 (Taroon Update 5), and 
> the imap server is CentOS release 4.1 (Final).
> 

The firewall could have restrictions on source IP.  Ferinstance, my server 
won't let me imap in from my server to my server because it won't accept 
packets where the source is its own IP address.  I can imap to localhost, 
though.