Issues with accounts, mail function disabled

OK or randomly my wordpress started throwing this weird “you host may have disabled the mail function” error when the the site tried to email someone when the email has to do this the account system. I don’t thing there is a good way to say this but it throws the error only when the site is working with accounts. But interestingly one of my plugins is easy digital downloads and when people are checking out then have to either sign into an account or make a new one and there the account system works perfectly. But there the user has to set the password so the site doesn’t have to email the password to the new user. But if I go through the normal registration process it wont email me the password it will say the mail function has been disabled. Also the download plugin has no problem emailing people their receipts, the issue is only with the default account creation. How can I fix this? and before you blame the host, its self hosted in a virtual host, other sites in similar virtual hosts on the same physical server hs no problem emailing people.