[PATCH 2/2] imap-send: accept messages with Subject before Date

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

From: Harald Nordgren <haraldnordgren@gmail.com>

Patches sent with git send-email cannot be fed back into git imap-send
after fetching them from the mailing list archive, for example with

    b4 mbox --single-message -o - <url> | git imap-send

which fails with "no messages found to send". imap-send only counts a
message when its From, Date and Subject headers come in that order,
and git send-email writes Subject before Date.

Accept the three headers in any order within the header block of each
message. The copy that git send-email --imap-sent-folder pipes to
imap-send then passes the same check, so the special case added for it
in 04133f5bc4 (send-email: add ability to send a copy of sent emails to
an IMAP folder, 2025-08-12) is no longer needed.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
 imap-send.c           | 37 +++++++++++++++++--------------------
 t/t9001-send-email.sh | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 20 deletions(-)

diff --git a/imap-send.c b/imap-send.c
index 6f76bade35..6563c8f693 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -1453,32 +1453,29 @@ static void wrap_in_html(struct strbuf *msg)
 	*msg = buf;
 }
 
+static bool has_required_headers(const char *line)
+{
+	bool from = false, date = false, subject = false;
+
+	while ((line = strchr(line, '\n')) && *++line != '\n') {
+		if (starts_with(line, "From: "))
+			from = true;
+		else if (starts_with(line, "Date: "))
+			date = true;
+		else if (starts_with(line, "Subject: "))
+			subject = true;
+	}
+	return from && date && subject;
+}
+
 static int count_messages(struct strbuf *all_msgs)
 {
 	int count = 0;
 	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 {
-				p = strstr(p+5, "\nFrom: ");
-				if (!p) break;
-				p = strstr(p+7, "\nDate: ");
-				if (!p) break;
-				p = strstr(p+7, "\nSubject: ");
-				if (!p) break;
-				p += 10;
-				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 d1393ef197..1f77c14315 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -2863,4 +2863,39 @@ test_expect_success $PREREQ '--compose handles to headers' '
 	test_cmp expect msgtxt2.to
 '
 
+test_expect_success $PREREQ 'imap-send accepts a sent patch from the list archive' '
+	write_script fake-imap-server <<-\EOF &&
+	printf "* PREAUTH [CAPABILITY IMAP4rev1 LITERAL+] ready\r\n"
+	printf "1 OK\r\n2 OK\r\n3 OK\r\n"
+	cat >/dev/null
+	EOF
+	test_config imap.tunnel ./fake-imap-server &&
+	clean_fake_sendmail &&
+	git send-email \
+		--from="Example <from@example.com>" \
+		--to=nobody@example.com \
+		--smtp-server="$(pwd)/fake.sendmail" \
+		HEAD^ &&
+	{
+		echo "From mboxrd@z Thu Jan  1 00:00:00 1970" &&
+		cat msgtxt1
+	} >archive.mbox &&
+	git imap-send --folder=INBOX <archive.mbox 2>err &&
+	test_grep "^Sending 1 message to INBOX folder" err &&
+	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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