[Imap-protocol] message sequence numbers vs. message UIDs

[Bill Janssen]

> In this system, the mailbox message sequence numbers are the same as
> the message UID numbers, so that's why you're seeing the same value in
> both places.  By the way, are there pitfalls with that design I'm not
> seeing?

I think I've answered this myself.  Yes, it's impossible to use the
same value for both, as message sequence numbers must reflect the
exact number of messages currently in a mailbox, while UIDs must be
continuously increasing.  The message sequence number is simply the
current one-based index of the message in the mailbox.

Bill