This might sound pretty basic but it caught me so maybe it'll help someone else. I did an automated profile link build on about 1K forums. Ran the email activation but missing a lot of them. The next day I'm getting ready to send out an article to a link wheel using the same email account and see a couple of late activations came in. Then it dawned on me to look in the spam folder (duh) and it was full of activations just waiting. Needless to say, got them over to the inbox and reran the activation module.