Folks, the subject line of an email is there to allow you to help people differentiate it from other emails. Do not use the same subject for every email dealing with the same superset. "Project X" is not a good email subject. "Developer documentation" is better. "Project X -- Location of developer documentation" is super, and helps you search efficiently, both by eyeballing and through mail client search interfaces, later.

That should be a no-brainer. See, you agree. You wonder why I wrote this. Then you don't use descriptive subjects. SHAME!!!