Title says it all really. 
I’ve gone to my settings to update the email address associated with my account.
It tells me an email has been sent to the new address, but I never received it unfortunately. (Even checked my spam folder)
I’ve tried it twice to make sure I didn’t spell the address wrong, but no luck.
I can see that the system honestly believes it sent you an email.
Unfortunately, my level of access won’t let me see folks’ email addresses, let alone change them, so must await a real two-badge admin. Sorry.
Even if you could, you would not be able to login unless you also update your default e-mail-address in your ubuntu one account. Whoever set up this discourse installation did a terrible job by locking anyone out of their account who had used a different e-mail-address before, and by using just that for authentication instead of some unique account id.