Comment 10 for bug 263293

Are you using the MSN - Advanced - Use Http method here?

Can you confirm the address you have in the block for http method. I have

gateway.messenger.hotmail.com

It looks like yours is not using http method.

From my debug without http method

11:55:39) connection: Connecting. gc = 0xa75c800
(11:55:39) msn: new httpconn (0xa7e8068)
(11:55:39) dns: DNS query for 'messenger.hotmail.com' queued
(11:55:39) dns: Created new DNS child 9035, there are now 1 children.
(11:55:39) dns: Successfully sent DNS request to child 9035
(11:55:39) dns: Got response for 'messenger.hotmail.com'
(11:55:39) dnsquery: IP resolved for messenger.hotmail.com
(11:55:39) proxy: Attempting connection to 65.54.239.210
(11:55:39) proxy: Connecting to messenger.hotmail.com:1863 with no proxy
(11:55:39) proxy: Connection in progress
(11:55:39) util: Writing file accounts.xml to directory /home/stefan/.purple
(11:55:39) util: Writing file /home/stefan/.purple/accounts.xml
(11:55:39) util: Writing file blist.xml to directory /home/stefan/.purple
(11:55:39) util: Writing file /home/stefan/.purple/blist.xml
(11:55:39) proxy: Connected to messenger.hotmail.com:1863.

I can also see that my messenger.hotmail.com resolves to 65.54.239.210 while yours is resolving to 65.54.239.20

This could be a regional thing as both of those addresses are listening on port 1863 (test by telnet 65.54.239.20 1863)
With this being said - does your network block outgoing to 65.54.239.20 on port 1863?

If so, try and use the http method and lets look at the debug log.