You posted at the wrong forum (because there's also a support forum), but I'll answer:
First of all, regarding messages that were already sent:
The FAQ wrote:Q. Can mail that is eaten be recovered?
A. No. It is never even written to disk.
While it doesn't cover "mail that is forwarded", I'd like to assume it's the same answer (and I wish someone will update the FAQ accordingly).
Secondly, better immediately log in spamgourmet.com and change to another protected address to avoid further lost mail.