home :: writing :: nullSender.txt
I am getting increasingly annoyed by the number of emails sent as responces to bounces. Particularly after the recent spates of viruses that forge all of the To, From and Sender addresses. I receive mail to the mailer-daemon at several sites. The only email ever sent with a from address of the mailer-daemon are bounces, and delay notifications. These are sent with a null return path (a sender header of <> ).
The RFC clearly states that software should NOT send automated messages to such messages. This is the point of a null return path. Just think what would happen if a recipient bounced these messages for some reason. It would create a mail loop.
RFC 2821 says:
If there is a delivery failure after acceptance of a message, the receiver-SMTP MUST formulate and mail a notification message. This notification MUST be sent using a null ("<>") reverse path in the envelope. The recipient of this notification MUST be the address from the envelope return path (or the Return-Path: line). However, if this address is null ("<>"), the receiver-SMTP MUST NOT send a notification.
Surely anyone writing software to automatically respond to email would have read this. Sadly this does not seem to be the case. If you are using such a piece of software, and have paid money for it, then I suggest you contact the authors and complain. It is only if customers complain, that things will actually get done.
For example, the following anti-spam pieces of software insist on replying to bounces. This just causes more and more hassle for mail admins.
- Mail Wiper - definitely appears to be the most popular piece of shit here
- ChoiceMail One
- R-Solution
- SpamEnder
- Spamchallenger
- SpamBan
- SpamArrest
- And several ones that appear to be cutom ones
I collected these names of software from just one afternoon's email to the mailer-daemon address. All of this is broken and just shifts the burden of spam from the person running them on to everyone else.
Last updated: 00:08, 29 Oct 2003 Link..