I'm trying to figure out how to disable storing sent messages in Mutt.
Is there a record value in .muttrc that would make it happen?
There's the copy option to control if copies of messages you sent are saved. It's a quadoption, so can be set to no (which would accomplish what you want), yes to save messages automatically, as well as ask-yes or ask-no to have it ask on each message with you being able to choose the default.