If you're looking for a modern email client with similar features, you may want to consider alternatives like Mozilla Thunderbird, Microsoft Outlook, or Google Gmail.

This is the most critical factor. Outlook Express 5.0 was built for an internet landscape dominated by simple text emails and basic HTML. It lacks:

Despite its flaws and age, Outlook Express 5.0 was a revolutionary product. It taught an entire generation how to manage email offline, use email signatures, and subscribe to newsgroups. Its compact database engine (storing messages in .DBX files) was incredibly efficient for the limited hard drive space of the late 90s (4–10 GB drives).