We are currently experiencing problems sending mails to Yahoo e-mail addresses. However, it appears that most mails are getting through after about 24 hours or so.
We are trying to fix the problem, but until it's fixed, we recommend one of the following:
Avoid using Yahoo e-mail addresses at BankrollMob. If you already created your account using a Yahoo address, then you can change it to ie. Gmail.com (recommended) at your Mob account and then "Edit account". Afterwards you can have a new activationmail re-sent.
Or, wait up to 24 hours and see if it appears in your Inbox by then. Do note, the mail can also go to your spam/junk filter, so be sure to check there as well.