Admin CP - Send Email to User

[MrEyes]

I have just tried to send a global email to all forum users, but it seems that nobody has received the email. When I sent the email I selected all users, and also included users that have declined admin emails. After submission I got a message something like this :

11 - username.... Emailing Okay
10 - username .... Emailing Okay
9 - username .... Emailing Okay
8 - username .... Emailing Okay
7 - username .... Emailing Okay
6 - username .... Emailing Okay
5 - username .... Emailing Okay
4 - username .... Emailing Okay
3 - username .... Emailing Okay
2 - username .... Emailing Okay
1 - username .... Emailing Okay

"username" replaces actual usernames.

This seems to indicate that there were no issues when sending the mail, but as mentioned above nobody has received the mail.

I have tested mail functionality on the server via my own PHP scripts, and also via the Admin CP - Diagnostics - Email tool. Both of these tests worked. This seems to indicate that email via VBulletin should be working correctly.

Does anybody have any ideas as to what could have happened here?

Regards
MrEyes