Pidgin and other working, non-microsoft clients don't use DNS for the passport server. After you connect to the initial server and handshake, giving user details and client information, msn servers then sent back a message directing you to the i.p. address of a server to authenticate. now Beup was never coded to extricate this address and use it, as newer clients do, but instead use the hardcoded I.P.s we are all used to seeing, which have had to be manually changed.
An excellent resource for MSNProtocol is: http://msnpiki.msnfanatic.com/index....Authentication it describes in great detail all the current protocols in use, including MSNP9, a variation of MSNP8, which Beup reports to use.