User can have @ in its name.
Ignore meaningless / in the end of URL.
Do not hide rows in administrative listbox.
Check that MailHost is sane.

getMessageList shall not be available on normal mail host. It will be available
on one coming from live tests, so in such case die immediately.
Do not play with smtp_url too early.

smtp_url can be None, so do not treat it as string, allow to take different
actions (like doing nothing).
Fix Typo
erp5_promise: correct bad syntax when there is no smtp auth.