@watcher
Thanks for the suggestion. I tried to use the web interface and I can communicate with the contact I was testing with.
Unfortunately this don't seems to affect MSN protocol in Miranda, and I still have the problems described above.
@Cool Javelin
I think that discontinue the MSN protocol in Miranda is not a good idea.
Many Miranda users have a significative part of their contact list with MSN protocol.
Skype protocol is closed and it is impossible to add it to Miranda after the Skypekit has been discontinued, so it is not a good replacement. The present Skype Classic protocol requires the use of the official Skype software, and it is too heavy for many not powerful computer where Miranda runs.
In 2013 Microsoft closed the MSN project but don't close the MSN network. Until they keep it alive, I think that MSN protocol in Miranda remains an important resource and it should be a priority to fix the problems that compromise its use.