On my website, I send an automated email using libmail.php for new sign-ups.
Users put in their email address and they are sent an email to activate their account.
This usually works for Gmail. However when a user signs up with Outlook.com, no email gets through to the user.
In my PHP code (libmail.php), I actually have done a BCC to another Gmail account from which I am sure that the activation email was indeed sent to the user, but it doesn't reach his Outlook.com email account.
Is there anything that I can do about this?