From 932a5acda1c5e5fddcc4fba7d249b2d2b0168fa1 Mon Sep 17 00:00:00 2001
From: Jameson Graef Rollins <jrollins@finestructure.net>
Date: Tue, 12 Apr 2022 13:03:53 -0700
Subject: new script to reinject message via sendmail(1)

This script simply takes an existing mail file, parses it for sender
and all recipients, and constructs an appropriate sendmail(1) command
to resend the message.

It requires the sendmail(1) binary at runtime, and the notmuch python
library in order to extract the message from an existing notmuch
store.

Signed-off-by: Jameson Graef Rollins <jrollins@finestructure.net>
---
 sendmail-reinject       | 73 +++++++++++++++++++++++++++++++++++++++++++++++++
 sendmail-reinject.1.pod | 45 ++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)
 create mode 100755 sendmail-reinject
 create mode 100644 sendmail-reinject.1.pod

diff --git a/sendmail-reinject b/sendmail-reinject
new file mode 100755
index 0000000..e50c484
--- /dev/null
+++ b/sendmail-reinject
@@ -0,0 +1,73 @@
+#!/usr/bin/env python3
+
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright 2022 Jameson Graef Rollins
+
+import sys
+import argparse
+import subprocess
+
+import email
+from email.policy import default
+from email.utils import parseaddr, getaddresses
+
+
+def sendmail(recipients, message, sender):
+    """send message via sendmail"""
+    cmd = [
+        'sendmail',
+        '-f', sender,
+    ] + recipients
+    print(' '.join(cmd), file=sys.stderr)
+    subprocess.run(
+        cmd,
+        input=message.as_bytes(),
+        check=True,
+    )
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Reinject an email message via sendmail.",
+    )
+    pgroup = parser.add_mutually_exclusive_group(required=True)
+    pgroup.add_argument(
+        'message', nargs='?', type=argparse.FileType('rb'),
+        help="email message path or '-' for stdin",
+    )
+    pgroup.add_argument(
+        '-i', '--notmuch-id',
+        help="message ID for notmuch extraction",
+    )
+
+    args = parser.parse_args()
+
+    if args.id:
+        import notmuch2 as notmuch
+        db = notmuch.Database()
+        query = f'id:{args.id}'
+        assert db.count_messages(query) == 1, "Message ID does not match exactly one message??"
+        for msg in db.messages(query):
+            path = msg.path
+            break
+        f = open(path, 'rb')
+    else:
+        f = args.message
+
+    # parse the email message
+    msg = email.message_from_binary_file(f, policy=default)
+
+    sender = parseaddr(msg['from'])[1]
+
+    # extract all recipients
+    tos = msg.get_all('to', [])
+    ccs = msg.get_all('cc', [])
+    resent_tos = msg.get_all('resent-to', [])
+    resent_ccs = msg.get_all('resent-cc', [])
+    recipients = [r[1] for r in getaddresses(tos + ccs + resent_tos + resent_ccs)]
+
+    sendmail(recipients, msg, sender)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/sendmail-reinject.1.pod b/sendmail-reinject.1.pod
new file mode 100644
index 0000000..f89d0f1
--- /dev/null
+++ b/sendmail-reinject.1.pod
@@ -0,0 +1,45 @@
+=encoding utf8
+
+=head1 NAME
+
+sendmail-reinject - reinject an e-mail via sendmail
+
+=head1 SYNOPSIS
+
+B<sendmail-reinject> B<message.eml>
+
+B<sendmail-reinject> B<-> <B<message.eml>
+
+B<sendmail-reinject> B<-i> B<messageID>
+
+
+=head1 DESCRIPTION
+
+B<sendmail-reinject> reinjects a message to your MTA via sendmail.
+The message is read in (via path, stdin, or from notmuch via message
+ID), the sender and recipients are extracted, and the appropriate
+senmdail command is contructed to resent the message.
+
+=head1 OPTIONS
+
+=over 4
+
+=item B<--notmuch-id>,B<-i> B<messageID>
+
+Message ID of message to reinject as know to a local notmuch database.
+Assumes the python3-notmuch package is available.
+
+=item B<--help>, B<-h>
+
+Show usage instructions.
+
+=back
+
+=head1 SEE ALSO
+
+sendmail(1), notmuch(1)
+
+=head1 AUTHOR
+
+B<sendmail-reinject> and this manpage were written by Jameson Graef
+Rollins <jrollins@finestructure.net>.
-- 
cgit v1.2.3