gmail has gone to complete sh|t lately. A lot of ISP's are denying anything sent from gmail with another domain name. If your friend did in fact enter the correct email address, and the confirmation wasn't sent, the only thing she/he can do is use another email address (from another ISP).
Check the spam/junk box, make sure the email adress was typed correctly. If its all ok, I suggest you PM Zise, the admin (red name) and explain the issue. The issue will then be resolved.