The domain name that is used to connect to Yahoo! servers is "scs.msg.yahoo.com".  This domain name is actually mapped to multiple servers.  Some of these servers have been upgraded, while others haven't.  As a result, you may see intermittent failures, or you may fail every time, while your neighbor logs in successfully.  It's effectively a roll of the dice.

The following addresses appear to work:

• cs101.msg.mud.yahoo.com
• 66.163.181.172

These are the IP addresses to which scs.msg.yahoo.com maps.  You can try one of them directly, but recent reports (on 6/19/2009) are that few, if any, are working.  Note also that there is no guarantee that the server at an address that works now will not be upgraded next.

• 76.13.15.36
• 76.13.15.37
• 68.180.217.6
• 68.180.217.7
• 68.180.217.8
• 68.180.217.9
• 68.180.217.10
• 68.180.217.11
• 68.180.217.12
• 68.180.217.13
• 68.180.217.14
• 76.13.15.29
• 76.13.15.30
• 76.13.15.31
• 76.13.15.32
• 76.13.15.33
• 76.13.15.34
• 76.13.15.35

You can verify this list yourself by running one of the following commands:

Windows: nslookup scs.msg.yahoo.com

Linux/Unix/OS X: dig +short scs.msg.yahoo.com

To use one of the addresses above, you can either modify the setting in Pidgin (Accounts -> Manage Accounts -> Modify -> Advanced -> Pager Server) or you can modify the hosts file:

Windows: C:\Windows\system32\drivers\etc\hosts (see wikipedia and here for more information)

Linux/Unix/OS X: /etc/hosts (see here for more information)

source:http://www.celticwolf.com/useful-information/faqs/26-pidgin-yahoo