I have had this problem for a few months.
When using the Evolution mail client, if I ever go to use the 'Backspace' key, it borks Evolution in several ways.
1. Using the key does nothing.
2. Once the key is used, say, while composing an email, then email will never send, comes up with an error.

How can I fix the keymapping so the 'Backspace' key works as it did?
Or, what packages need re-installing?
I have a complete backup of the .evolution folder, and have backups made from within Evolution itself, but I am afraid of losing data for all my mail servers, passwords, etc. The thought of having to re-enter all that info again could become a nightmare.