phpmailer sending email within same domain fails??

i don't get this i am using phpmailer class to send emails.

A/1 form confirmation email to the user ($useremail)
B/1 email to a department (department@domain.com)
C/1 email to myself for check (me@mydomain.com)

$mail->AddAddress("$useremail","$username");
$mail->AddBCC("department@domain.com","Form on website");
$mail->AddBCC("me@mydomain.com","Form on domainwebsite");

Code (markup):

A en C are being sent but B isn't???The only difference is the fact that case B the domain name = email domain name.

Any advice, info on this???

 

Do you get a forged from header error?