Is there a “no-reply” email header?

Question

I often see automated emails postfixed with a message like

Amazon:

*Please note: this e-mail was sent from an address that cannot accept incoming e-mail. Please use the link above if you need to contact us again about this same issue.

Twitter:

Please do not reply to this message; it was sent from an unmonitored email address. This message is a service email related to your use of Twitter.

Google Checkout:

Need help? Visit the Google Checkout help center. Please do not reply to this message.

Directly underneath this warning, Gmail shows me a reply input field. It seems to me that there should be some sort of header that could be attached to such automated emails that would tell the recipient's email client to not allow replies.

Is there such a header? If not, has it ever been discussed by the groups that control email formats?

Answer 1

Is there such a header?

No. I'm pretty sure there isn't anything like that; and even if there is, it'd be non-standard and not widely supported, so it'd be pretty much useless at the moment. Even if it were to become standard, any such header would presumably just be informational; and for backwards-compatibility, support would have to be entirely optional for email clients. Clients would be slow to implement it, and many users would still be on old versions of mail clients.

If not, has it ever been discussed by the groups that control email formats?

Probably. People have had a long time to suggest all manner of things with email, but my gut feeling is that it would never be implemented; well... not unless there is a fundamental shift in the ideas of what email is designed to do. I'm sure Google would be much happier if you didn't even have a "Reply" button when they email you, so if anyone is pushing for it, it'll be the people who are already sending from donotreply@...

Email is designed to be sent from real mailboxes. RFC 2822 and RFC 5322 say:

In all cases, the "From:" field SHOULD NOT contain any mailbox that does not belong to the author(s) of the message.

To me, that is a clear indication that email is designed as a method for conversation, rather than broadcast.

Probably the biggest killer to any change would be the little bit above that line, which would need to be entirely redefined; which would cause more problems than would be solved:

The originator fields also provide the information required when replying to a message. When the "Reply-To:" field is present, it indicates the address(es) to which the author of the message suggests that replies be sent. In the absence of the "Reply-To:" field, replies SHOULD by default be sent to the mailbox(es) specified in the "From:" field unless otherwise specified by the person composing the reply.

Answer 2

No, there's no no-reply header.

However, you can add an empty reply-to header:

reply-to: <>

Which is valid according to RFC 5322, Section 3.6.2. Unfortunately, the RFC never actually specifies what an empty reply-to field means. I think most email clients just ignore it.