whats the best way to manage different mail accounts on mavericks ?

Mail app works just fine with more than one account.

A drafts mailbox will be created when one is needed. If you have multiple accounts, the draft messages would be handled independently for each. Simply trying to close down a message in progress would offer you the option to save it in a draft area.

Drafts are just that - temporary draft files. The drafts box is removed when you do stuff like initialize the app.

I've never even tried saving draft files when closing the Mail app. It could be that an act like closing the app removes the drafts mailbox. I know for a fact that the drafts mailbox is removed when it is empty and the mail app is closed.

Outbox behaves similarly. It is certainly removed when the mail app is closed. In fact, I see it disappear each time the mail is successfully sent from it. In other words, if I have a message that takes 10 seconds to transmit, once the message is sent (10 seconds), the outbox is obliterated.

That would depend on two things:

1. Your backups

2. What mail app you were using previously, and whether or not you saved backups from it.

Oh, so if your mail account's host server retains copies of your drafts, then you can get them there (through your browser).

I suspect they do not and you have no drafts available, but I might be wrong.

Personally, I would never do that. So I cannot answer. I would always finish my work and never ever have the need to save a draft overnight.

I suggest you try it and see.