Gets the index of the mail message stored on the mail server.
Gets the ordinal position of the mail message in the mailbox on the mail server (starting from 1), or 0 if this message was created from another source rather than received from the mail server.
Use UidOnServer property if you need to determine Unique-ID of the message rather than its ordinal position in the mailbox.
MailMessage Class | MailBee.Mime Namespace