You are talking about something like this, right? Looks reasonable to me.
No hurry.

Sorry, if this mail does not show up correctly in the thread. I cannot get mutt
to authenticate to the gmail account. So I really used vi and sendmail -t.


Index: usr.sbin/smtpd/smtp_session.c
===================================================================
RCS file: /cvs/src/usr.sbin/smtpd/smtp_session.c,v
retrieving revision 1.442
diff -u -p -u -r1.442 smtp_session.c
--- usr.sbin/smtpd/smtp_session.c	20 Mar 2024 17:52:43 -0000	1.442
+++ usr.sbin/smtpd/smtp_session.c	8 Sep 2024 06:48:13 -0000
@@ -2625,7 +2625,7 @@ smtp_tx_dataline(struct smtp_tx *tx, con
 
 		case RFC5322_END_OF_HEADERS:
 			if (tx->session->listener->local ||
-			    tx->session->listener->port == htons(587)) {
+			    tx->session->flags & SF_AUTHENTICATED) {
 
 				if (!tx->has_date) {
 					log_debug("debug: %p: adding Date", tx);