Hi,
I don't think that there's a perfect answer. There is a work around I use if you use a mail client such as Outlook.
1. Create a POP mailbox and add the mailbox as an e-mail queue in Kayako.
2. Add the POP mailbox to the list of mailboxes in your mail client.
3. Register your e-mail address as a catch-all rule.
Now you can drag and drop offending e-mails from your Inbox into the new POP mailbox. The mail is the parsed and logged against the ticket.
You might also be able to change the from and To addresses with a similar technique but that's plain naughty
Rob