Lijkt er wel op Ivan1986.

Ik gebruik Pindgin maar heel sporadisch.
Ik vond dit op hun site, misschien heb je er iets aan, ander moet je toch bij hun op de site verder zoeken.
http://developer.pidgin.im/search?q=blocking&noquickjump=1&ticket=on&milestone=on&wiki=onHow do I get blocking someone to work?
There is a known bug in the Yahoo! protocol code present in libpurple. We've been unable to determine the exact cause or a workable code solution to the problem, but the failure seems to be most prominent when the blocking code tries to automatically remove the buddy from your list (this is required for a block on Yahoo!). It will also always fail if libpurple thinks the buddy is already blocked.
We suggest manually removing Yahoo! buddies before attempting to block them. For buddies reported as already blocked who are not in fact blocked, unblock them (in Tools->Privacy) and block them again. This works often.
Met vriendelijke groet,
Gijs