Thanks. I tried that route, but Postfix only writes X-Original-To in its own final-delivery agents (local, virtual, pipe); the lmtp client doesn't add it. Of 18 messages delivered over LMTP in the last day, 17 have no X-Original-To, and the one that does carries lists-debian-security-announce@bendel.debian.org, inserted by Debian's list server upstream.
That second point is why I'd rather not rely on the header fallback: it reads whatever X-Original-To the message arrives with, so the "original recipient" can be set by a remote server or by the sender. ORCPT comes from the delivering MTA in the envelope and doesn't have that problem.
So the request stands: could LMTP advertise DSN (optionally behind a setting) so MTAs send ORCPT?
On (Tue) Oct 20, 2026 11:00 am, Stephan Bosch via dovecot <dovecot@dovecot.org> wrote:
Op 9-10-2026 om 22:29 schreef Dhaval Patel via dovecot:
If there's an existing way to get this that I've missed, I'd be glad to hear it.
https://doc.dovecot.org/2.4.5/core/summaries/settings.html#lda_original_reci...:
lda_original_recipient_header
The header from which the original recipient address (used in the SMTP RCPT TO: address) is obtained if that address is not available elsewhere.
With LDA the default is based on the username in -d parameter. With LMTP Server the default is the same as RCPT TO.
Example:
lda_original_recipient_header = X-Original-To
https://www.postfix.org/postconf.5.html:
enable_original_recipient (default: yes)
Enable support for the original recipient address after an address is rewritten to a different address (for example with aliasing or with canonical mapping).
The original recipient address is used as follows:
Final delivery With "enable_original_recipient = yes", the original recipient address is stored in the X-Original-To message header. This header may be used to distinguish between different recipients that share the same mailbox.
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