mIRC by default would not auto-accept .INI files, there was a blacklist on certain file types that would be rejected, with INIs as one of them.
Was that a reaction to the problem described in the GP? Especially in the 80s/90s, defensiveness like that was probably to solve an existing problem.
It would attempt to send to people as they joined a channel.
More info: http://www.irchelp.org/security/si.html