No emails

A few people tried to join my forum, but they said they never received the email from Forumotion which would allow them to sign-in to the forum. Would someone know why they did not receive that verification email? I believe they are all using AOL mail. They even checked the spam folder and nothing there either.

(I know I can authorize their membership from my Admin page, but then again, I wouldn't know if others who have tried to join have not received their email authorization either.)

There is no other way to know.