- add debug mode. if in the debug mode, it will send the mails without
any CD time. And it only use my Gmail account as the receiver so that
the other admin will not receive this DEBUG mail.
- send the mail with HTML header so that we can use <pre> label to show
the ascii emoji
- the filter with detecting multi card in the same server, but only
retrive the first user in the list.
- get Gmail private code with the enviroment variables.