I want to send an e-mail from our system to customers, where some tags should be hidden to them. I\'ve set the following CSS:
.hidden { display: none; }
Outlook 2007 has limited support for CSS and HTML. Read this article for more information.
If class-based CSS rules don't work, try ID-based CSS rules. Just try to keep your rules as simple as possible.
You can use this tool to validate your HTML and CSS for use in Outlook 2007.