Italki has a lot of bugs, especially when it comes to sending out mail (and notification of any kind, really). Since you are already posting here, I assume your profile is already active and you can use the website. Just make sure you check for messages, friendship invitations, etc here instead of waiting for them in the mail. If you really feel you should bring this up with the italki team, I guess you'd have better luck if you use the Feedback form (upper right corner of your screen).