I'm thinking it has to do with the [dot] in my main email address and the [underscore] in my alt. Will be trying again eventually with a St0rm.net E-mail address, just have to get Wilo to set it up.
EDIT: Turns out, you can't use capital letters in you're email address when signing up. Nothing to do with the email provider or [special characters]. My emails happen to have capital letters in them both, and they both worked after typing them in lowercase. Just need to find how to delete the one I didn't want now.