Vim tw={80=>76}

This provides room for three-digit line numbers, plus a delimiting space, on
an 80-character terminal. If additional lines numbers are needed, the file
is probably too big.

This is also more polite for e-mail.
Encrypting sent mail using my public key

Allows me to decrypt sent mail for future reference. Disallowing decryption
by myself is not much of a practical concern, since replies are generally
quoted. That said, if it were ever a concern, this could be easily disabled.