Thread:Project:Support desk/Mediawiki can't send e-mail (fifth parameter in mail)/reply

Well, it's not a problem with MediaWiki, but a problem with a bad hosting provider. If I were you, I'd go and find a better one. It's hilarious how they claim One.com's servers run with safe mode set to off but they have turned off PHP features as if safe_mode is enabled.

I'm curious to see if they really have safe_mode active, since MediaWiki does various checks for that condition, in which case it shouldn't fail, and you should file a BUGREPORT about that. Otherwise, there's not much we could do about this if bad hostings disable random functions and function parameters.