Forums / Cotonti / General / Not receiving mail from PM's

I've also tested here on Cotonti website and I got the notification mail...
but this is not the case from my website. Only in this case my site doesn't send mails, all other parts of the site is sending mails regulary, so it isn't a spam protection or other similiar problem.
I've also diabled a plugin that notified new pm presence with a popup (I was thinking about a hook conflict), but the problem is still present...