I got an email invitation to 'collaborate on code on Bitbucket'. (You've been invited to collaborate on code with xxx on Bitbucket) I accepted the invitation. Then I got a '[Bitbucket] Confirm your email address' with a link that will take me to my home page with the warning 'We were unable to confirm the email address. The validation email may have expired'.
Maybe the email confirmation is not necessary when I was invited?