[ using mailcrypt 3.5.5 ]   

By default, the public keys that are looked up are the based on the
recipient email ids in the message.  I want to specify another key
instead (say because I am sending a message to a friend who uses the
same gpg key pair on different acounts).  If there is a legit way of
doing this, pray explain it and ignore the rest of this mail.

As I could not get to do the above, I executed the following patch: