I wasn't able to find this posted anywhere else here, so I thought I'd mention it. Yahoo appears to have changed their default server from scs.yahoo.com to scsa.msg.yahoo.com. The former is still up, but doesn't appear to communicate with the others. The result is that if you login on scs.yahoo.com and one of your buddies logs in on scsa.msg.yahoo.com, you won't be able to communicate with one another. For those using Yahoo messenger, this isn't a big deal, as the software adjusts automatically. Those of us that use Trillian or GAIM (and probably any other third party clients) are going to need to change the server manually.

For reference, the following is a list of known Yahoo Messenger servers and ports taken from Trillian's message boards:

scs.msg.yahoo.com
scsa.msg.yahoo.com
scsb.msg.yahoo.com
scs-fooa.yahoo.com
scs-foob.yahoo.com
scs-fooc.yahoo.com
scs-food.yahoo.com
scs-fooe.yahoo.com
scs-foof.yahoo.com
cs81.msg.sc5.yahoo.com
cs108.msg.sc5.yahoo.com
cs114.msg.sc5.yahoo.com
66.163.169.213
216.136.173.142
216.136.173.171
216.136.131.64
216.136.227.25
216.136.227.76
216.136.227.79

Ports:
20
23
25
80
119
5050
8001
8002

Why Would Yahoo do that to there servers?

Well...the official story seems to be that they were doing server maintainence, presumably on that server, last weekend. Could be they screwed something up by mistake and haven't really noticed it yet as all the authorized clients are still connecting without problems.

Other possibility is that they wanted to block third party clients (ie, Trillian, GAIM, etc.) with something that would be slightly tougher to work around. It's not an obvious block, as you still appear to be online and can even communicate with anyone connected to that server, so it would take some time for enough people to even notice, much less report it to someone that could issue a patch. I'm not saying this is what they did, but it's certainly a possibility.

thanks, updated gaim to scs.msg.yahoo.com:5050