[Evolution] Modify incoming messages

[linux4cyril free fr]

Hello,

First, I would like to congratulate the team for the great work done on 
Evolution. This is really a nice tool. Thanks !

I have just a little question. I would like to change the subject and the 
content of some messages are receive. Say to put a subject that will fit to my 
mind and at least remove footer/signatures 10 lines long.

Can you tell me how I can do that ?
I am using the release 0.12.

Thanks,
Cyril