Eclipse Mail, an email client for Windows XP and IA-32 i686!
Eclipse Mail is a fork of Interlink Mail and News made for Windows XP and runs on IA-32 i686 platforms. Some advantages over upstream and roytam1's mailnews are more optimizations and better interoperability with upstream. (using SQL storage intead of DBM)
Main download link (GitHub)
Alternative download link (SourceForge)
Features
Installer and true portable varaints
Compatible with IA-32 i686 class hardware
More optimizations than upstream
Uses SQL instead of DBM for better compatibility with upstream profiles.
JPEG XL support