Each e-mail message is assigned a unique Message ID (e.g. o7IBY66I013204) by each mail server the message is relayed through. Often these Message ID's are recorded by the mail server in a Received: e-mail header. The PerfectMail message view page shows the Message ID for each message at the top of the page.
You can use the Message ID to locate e-mail exchange details in the Raw Log for a specific message; or inversely use the Message ID from the Raw Log to locate and display the contents of an actual e-mail.
When tracking the progress of an e-mail, take a close look at the "stat=" portion of log entries in the Raw Log. The "stat=" will say what happened to the e-mail and will often give the Message ID that was assigned to the message on the mail server it was sent to.