Sanitized sendmail's from_addr parameter.

or Mail.send_message with MAIL_DEFAULT_SENDER as ('XXXX', 'no-reply@xxx.com') will raise exception: SMTPSenderRefused(501, 'mail from address must be same as authorization user', ('XXXX', 'no-reply@xxx.com'))
Merge pull request #39 from mrluanma/master

Sanitized sendmail's from_addr parameter.