This is the software publishers description.

A useful browser plug-in that helps you identify legitimate email messages in your inbox. It uses a two-step check to verify the authenticity of messages from hundreds of major companies, and then displays the result in the “from” area so that you'll know what's real. This helps you avoid opening and acting on phishing messages attempting to spoof real companies.

Trend Micro eMail ID helps you avoid fake messages and risks associated with them. It also helps you find legitimate messages quickly and gives you the confidence to open and act on those messages. It complements Trend Protect and other Trend Micro tools and products by operating directly in your email client, helping you have a safer and more productive online experience.

It also enables you to add Truemark icons to your email inbox and open messages to indicate legitimate messages from hundreds of major companies. It operates in a similar fashion across all webmail clients and Outlook Express, so you don’t have to learn a different interface as you check your email in different clients.