In order to simplify auto-response suppression and other filtering, I want to synthesise an Auto-Submitted header on notification mails that should have them but do not.

In a sieve file I add the following:

if anyof ( header :contains ["From","Sender"] “info@example.com" ) { if header :contains "Subject" [" just joined "," just left "] { if not exists "Auto-Submitted" { addheader "Auto-Submitted" "auto-generated (via sieve)"; } }

However this doesn’t work and results in the following error

main script: line 205: warning: addheader action: specified header field `Auto-Submitted' is protected; modification denied.

(Workaround for this specific issue would probably be to use a List-* header instead.)

Looking at http://hg.rename-it.nl/dovecot-2.2-pigeonhole/file/c8edece267cd/src/lib-siev... I can see that "Auto-Submitted” and “Received” are hardcoded to be blocked without reference to whether they are to be added or removed.

However, the hard restriction in RFC 5293 on Auto-Submitted and Received only applies to the use of deleteheader and not addheader.

https://tools.ietf.org/html/rfc5293#section-6

As a matter of local policy, implementations MAY limit which header fields may be deleted and which header fields may be added. However, implementations MUST NOT permit attempts to delete "Received" and "Auto-Submitted" header fields and MUST permit both addition and deletion of the "Subject" header field.

Using Dovecot version 2.1.7 but I assume it’s not version specific issue.