Looking through http://groups.google.com I discovered many of my old posts. At the time I had a timeshare account through Florida International University. I was 19 and a big advocate of the Amiga at the time. My timeshare account was offered through the Southeast Regional Data Center (SERDAC), which was one of multiple division data centers created in Florida and connected via the Florida International Resource Network (FIRN). FIRN was largely connected via X.25 using TymNET software. My email address at the time was firstname.lastname@example.org.
For sure, I have emails going back much further than this, at least until 1985, but I have been unsuccessful in finding archives.