RemoveAll method will remove all messages from the
mailbox file, or all parts from some message. However,
contents of the mailbox will not be updated until you
manually call Update
If current Message object represents part of another
message, then it will remove all parts from that particular
message. Same as before - you have to call Update to make
actual changes in the mailbox file.
To see the difference,
mailbox.RemoveAll will remove
all messages from the mailbox
mailbox.Message(0).Parts.RemoveAll will remove
all parts from first message.