The /ignore command
I don't think there is a XEP that describes how to do that. And I believe it will be specified in any XEP. But the /ignore command, for the MUCs is really needed, IMO.
/ignore <nickname> should add "muc@server.tdl/nickname" in the ignore list, and gajim would ignore all messages (private or not) coming from this personne. /unignore <nickname> should remove "muc@server.tdl/nickname" from the ignore list
(we could also have a command that let us see all the nicknames in the ignore list)
This could be implemented client-side-only.
I don't know if this was ever asked, but I think it's a great feature that is missing... What do you think ?