Microsoft Outlook Express

ABF Outlook Express Backup
Backup and synchronization tool for Outlook Express mail client. The user interface is multilingual. English, French, Russian, and Macedonian languages are supported.
http://www.abf-soft.com/outlook-express-backup.shtml

Fidolook
Freeware extension that provides enhancements and capabilities for Microsoft Outlook Express. Provides templating and customization, access for working with raw headers, folder options and allows importing and exporting of messages.
http://www.fidolook.org/

OE-Backup.
Backup and restore utility for Outlook Express 5 and higher. Backup mail folders, mail accounts, message rules, signatures, stationery, and all personal settings.
http://www.oe-backup.com/

OE-QuoteFix
Add-on that modifies message composition windows on-the-fly to allow for 'correct' quoting, compressed indentation, and RFC-compliant signatures.
http://home.in.tum.de/~jain/software/oe-quotefix/

Stationery by Teresa
Outlook Express stationary files.
http://www.teresasstuff.com/Stationery/stationery%20index.htm