Symptoms
When the e-mail confirmation is setup in PBA, the customer is asked to confirm an e-mail. When the customer changes his/her e-mail address from the customer's control panel, a warning appears:
Your changes have been saved. Please be aware that your email address is not confirmed. Confirmation email is sent to OLD_USERS EMAIL address. Click the link in the letter to confirm the address.
But that is not true, confirmation email is actually sent to a new e-mail address.
Cause
The issue is confirmed as a bug, its id is #PBA-57714 ("Message about confirmation email shows wrong address").