Sometimes, in the heat of getting a lot of things done, I don't read emails I send as closely as I should. Is there an automated way to pop up warnings before a potentially-unpolite email is sent? I'm thinking about something that would say "wait, why don't you have a 'please' or 'would you' in that message?"

I'm using Thunderbird 2 on Ubuntu 9.04. I may be willing to switch email clients if another program offers this.

Thanks for your help!