One of our suggested messages contains an image with a hyperlink. However, when a participant tries to use it within the participant center, it says "The message contains invalid HTML tags. Remove them and try again." In the received message the image and hyperlink were not there.
This is the default behavior - it can be altered. There are three settings that affect this, listed below. Contact support to have this settings altered.
Allow images to be inserted with <img> tags.
Allow links to be inserted with <a> tags.
Allow admins to configure suggested email message templates using a WYSIWYG.