feature: compose: allow not storing the sent emails

[laarmen]

I'm using lieer/gmi to send email, and it has the builtin assumption
that no new messages will be added to the maildir.

See gauteh/lieer#54

[akissinger]

I understand making it optional for Dodo to save the sent message, but it doesn't seem particularly helpful to split this small block of code into its own function with an early return, rather than just having a nested if statement.

[laarmen]

Force of habit. Splitting standalone code in free functions with defined semantics helps in testability (not applicable here though), makes it easier to use local reasoning (no variable shadowing, no mutating self), reduces cyclomatic complexity, reduces overall indentation level, etc... which has always helped me in the long run. Ironically, code reuse (which is the initial raison d'être of functions, after all) is really far down the list.

I can redo the patch to do it all inline if you prefer, though.

[akissinger]

I can understand that. I think it this case it's overkill though. I'd just shift the 2 statements to after where the setting is read and wrap in an if.

[laarmen]

Fair enough, done.