[PATCH v4 3/4] imap-send: check git send-email copies like other messages

["Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com>]

From: Harald Nordgren <haraldnordgren@gmail.com>

The copy that git send-email --imap-sent-folder pipes to imap-send
starts with a "From git-send-email" line. 04133f5bc4 (send-email: add
ability to send a copy of sent emails to an IMAP folder, 2025-08-12)
made imap-send count such a message when it has From and To headers,
without looking for Date and Subject. Without that special case the
copy would not be counted at all, because git send-email writes
Subject before Date.

Now that the headers are accepted in any order, the special case is no
longer needed. The copy carries the same headers git send-email sends
over SMTP, which always include From, Subject and Date, so it passes
the check for other messages. A To header is no longer required, the
same as for any other message.

This makes the check stricter when some other script writes an mbox
with a "From git-send-email" line. RFC 5322 requires a Date header but
only recommends Subject, so a valid message from such a script may
lack a Subject and would no longer be counted. imap-send has always
required a Subject under any other "From " line, though, and only
refuses an mbox when none of its messages are counted, so treating
these copies like the rest should not affect anyone in practice.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 imap-send.c           | 15 ++-------------
 t/t9001-send-email.sh | 13 +++++++++++++
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/imap-send.c b/imap-send.c
index 8977a934f8..706c517e51 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -1478,19 +1478,8 @@ static int count_messages(struct strbuf *all_msgs)
 	char *p = all_msgs->buf;
 
 	while (1) {
-		if (starts_with(p, "From ")) {
-			if (starts_with(p, "From git-send-email")) {
-				p = strstr(p+5, "\nFrom: ");
-				if (!p) break;
-				p += 7;
-				p = strstr(p, "\nTo: ");
-				if (!p) break;
-				p += 5;
-				count++;
-			} else if (has_required_headers(p)) {
-				count++;
-			}
-		}
+		if (starts_with(p, "From ") && has_required_headers(p))
+			count++;
 		p = strstr(p+5, "\nFrom ");
 		if (!p)
 			break;
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index d105fcb41c..1f77c14315 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -2885,4 +2885,17 @@ test_expect_success $PREREQ 'imap-send accepts a sent patch from the list archiv
 	test_grep "(1/1) done" err
 '
 
+test_expect_success $PREREQ '--imap-sent-folder stores a copy of the sent patch' '
+	test_config imap.tunnel ./fake-imap-server &&
+	clean_fake_sendmail &&
+	git send-email \
+		--from="Example <from@example.com>" \
+		--to=nobody@example.com \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		--imap-sent-folder=Sent \
+		HEAD^ 2>err &&
+	test_grep "^Sending 1 message to Sent folder" err &&
+	test_grep "(1/1) done" err
+'
+
 test_done
-- 
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