This plugin for Trac >= 1.1.3 stores the Message-ID of ticket notifications in a new database table, so they can be used for the In-Reply-To header of subsequent messages.
This is necessary when using Amazon's Simple Email Service (AWS SES), because it rewrites the message id. It is also useful when changing the project URL or sender domain (otherwise replies will end up in a new thread).
It is a drop-in replacement for the native SmtpEmailSender component.
Deploy to a specific Trac environment:
cd /path/to/pluginsource
python setup.py bdist_egg
cp dist/*.egg /path/to/projenv/plugins
Or install globally:
cd /path/to/pluginsource
python setup.py install
Enable plugin in trac.ini:
[components]
tracmessageid.* = enabled
[notification]
email_sender = MessageIdSmtpEmailSender
Upgrade the database:
trac-admin /path/to/env upgrade