Mark what generated the message
04Auto-Submitted describes whether mail came from a human, an automatic generator, or a direct automatic reply. It is not a security credential.
The valid example auto-replied; x-demo=1 is still recognized as auto-replied. Parameter processing must not turn it into human mail; this example parameter is experimental.
Source for this drawing: RFC 3834 · Read RFC section 5.2 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
These pictures are analogies to help you learn. The linked RFC explains the actual rules.
Terms in this drawing
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
Auto-Submitted: auto-generated SHOULD label automatic mail that is not a direct response. It MUST NOT label manually generated messages, direct replies, or delivery/disposition reports.
- Auto-Submitted: auto-generated SHOULD label automatic mail that is not a direct response. It MUST NOT label manually generated messages, direct replies, or delivery/disposition reports.
- Auto-Submitted: auto-replied SHOULD label direct automatic responses, MUST NOT label manually generated mail, and MAY label DSNs/MDNs. Human mail SHOULD normally omit the field; no MAY explicitly indicate human origin.
- At most one Auto-Submitted field is allowed. Syntactically valid optional parameters MUST NOT prevent recognition of the field and keyword; implementations MAY ignore those parameters. Treating any non-no keyword as automated remains useful for extension values.
- The Auto: subject prefix MAY help humans, but software SHOULD NOT use it as proof that the message is automated. The header is also forgeable: no, or absence, does not authenticate a person.
Fictional example.org addresses. Independent examples are labelled; this is guidance for responders, not a full mail parser or an authentication mechanism.
Read the RFC section ↗