The networks
Since Microsoft closed Messenger, volunteers have brought it back on servers of their own. MiXiN Messenger signs in to four of them, as many at once as you have accounts on. Your account stays with the network; MiXiN just signs in to it for you.
Escargot
MSNP18
The longest-running revival. Works with nearly every version of Messenger, from the very first.
CrossTalk
MSNP18
A newer network with its own community. MiXiN saves your picture and personal message to CrossTalk's storage, so they show on crosstalk.im too.
Kring Alpha
MSNP3 to 21
A young network. You sign in with your Kring address, name@kring.im, and its password.
OMessenger Alpha
MSN 1 to 7.5MSNP12
For the classic MSN Messenger crowd. Its server doesn't keep nicknames, favourites or offline messages, so MiXiN keeps them for you.
A word about the networks
Each network is run by its own people, with its own rules, and MiXiN isn't connected with any of them. Please follow each network's rules. And if something goes wrong while you're using MiXiN, it may well be MiXiN rather than the network.