outbox and sentbox

Could someone please tell me what the difference between these boxes are? Some of the messages I have sent are in one and some in the other.

Also, I suspect some people have not received my messages.

Len

As i know, in the outbox sitting messages not sended, and the sentbox contains the sended messages. The new writed message go to outbox only if You work without connect, but maybe depend from settings.
When i click on send/receive, from outbox send all messages.(MS outlook express)

Outbox: waiting to send, ready to send, messages not sent due to connection problems ?

Sentbox: a kind of ARCHIVE of messages successful sent.
So if you want to add comment to a message already sent,
or just want resent, the message be found there.

Thanks. So they are analogous to the folders in MS Outlook