I got this when sending an ssh key change request:
Your request to the mail gateway is malformed, or an internal processing
error occured. The information below may help you, or the gateway
administrator to identify the problem.
Error: Unable to check the signature or the signature was invalid:
==> <type 'exceptions.TypeError'>: exceptions must be old-style classes or
+derived from BaseException, not str
Please email email@example.com if you have any questions.
I've made some changes to the mailgate now, and it should give better error messages when something is wrong. Could you please try again?