This error appears only in the error log and it does seem that affects nothing on the long term. I had guest that this error only appears when users try to set a new avatar photo and then they got this message:

[code][phpBB Debug] PHP Notice: in file /includes/functions_messenger.php on line 1565: mail() has been disabled for security reasons[/code]

Also, together with the message above, there are also the following message:

[code]Eroare e-mail
» EMAIL/PHP/mail()
/cron.php[/code]

Everything started on 1st of July and i did not to any modification to the source since several days before that happend.