Clarification of private messaging features

[zeke]

Is there a section in the FAQ that explains how to use the private messaging feature?

What is the difference between the sentbox and the outbox? I have a message that appears in both. I have a message which I hope was sent to the intended receipient yesterday, which appears in the outbox and not the sentbox. What does that mean? What is the best way for me to see that a message was actually sent?

Does outbox mean that the message was not sent? If so, is it possible for me to retry sending it?

Is it possible to save a message and return later to edit it?

Thank you!