Let's say emails from a specific SaaS provider come from their domain saasprovider.com and all the emails look like this:

Subject: Notification blah blah
Body: Consists of HTML links and stuff
Attachment: PDF file

Is there a way to have Zimbra rewrite the Subject and Body of the email before delivering to the user's mailbox? The attachment should be used unmodified, but the subject and body need to be modified.