7
This is actually not a fix...
Switching to "php mail" solves the problem cause it uses a different send method (the one which uses the php mail function).
If you like to use SMTP:
1.You switch to SMTP method for sending mail as admin;
2.You go in the site with a normal user account and, when you set the mail account, you need to provide a valid email address in the FROM field (this is what kaotik was trying to suggest you).
Bye,
ft