Imap connectivity issue

["Joyce, Matthew" <MJoyce@ccia.org.au>]

Hi,  

I have Deb v3 k2.4.18 running uw-imap.

I can connect from the same network with a client.
But not from home.

I am assured the network guys have made the correct changes to our routers
ACLs to allow port 143.

>From another home....

nmap xxx.xxx.xxx.xxx -p 143

Starting nmap V. 2.12 by Fyodor (fyodor@dhp.com, www.insecure.org/nmap/)
Interesting ports on  (xxx.xxx.xxx.xxx):
Port    State       Protocol  Service
143     filtered    tcp        imap2

Nmap run completed -- 1 IP address (1 host up) scanned in 1 second

What does 'filtered' mean ?
Is the TCP wrapper doing this ?
Do I have to specifically allow access from other networks ?

thanks

Matthew Joyce