I'm quiet sure this isn't a mIRC socket bug...
And i'm also sure (unless its changed very recently), that you're meant to get the ticket from a HTTP authentication server, and you send that to the MSNPXX servers.
Specifically: sockopen -e msn.authserver login.live.com 443
I'm quiet confident in this, because when MSN Chat was open, it was faster to use the Messenger authentication server to receive the encoded passportticket and passportprofile authentication keys
