in the mid 90s i worked in a machine shop that had a side business where they had catalogs. They were trying to send .TIFF files over 14.4 or 28.8 modems. TIFF files over 10MB, so no floppy (easily.) No CD-R, Jazz/zip.

These days in the same circumstance as you (and they) had, i'd fedex them a USB stick, or optical disc, depending. Because the first time someone said "the web page you linked is just displaying garbage" i'd turn in my tech credentials, because that's probably my server's fault, not the browser. MIME has been a thing for three decades, at least. it sounds like someone tried to use a static html daemon to share a zip file, and it assumes everything is ascii. like it's 19xx and zmodem hasn't been invented yet.