A desktop publishing application from Microsoft that focuses on page layout and graphic design.
Frequently there is no HTML equivalent for print formatting. Thus Publisher does the best it can by approximating what you wanted. Frequently it converts a block of text into a picture which will kill the hyperlink.
You can deconstruct your invitation to a simple text box of a web friendly text, no borders, no infill, no special formatting, not pictures and test. If successful then add one level of formatting at a time testing as you go until you find what causes the problem. Follow the KISS principles.
However there is no way to know if the recipient's email client will read the message correctly. They may have their client set to reject pictures for example or to only show plain text.
Bottom line is if you don't want to use an attached PDF, then consider using a third party program that is designed for this. www.constantcontact.com or www.group-mail.com and a free version: http://www.group-mail.com/asp/common/downloads.aspor another popular one is http://mailchimp.com/ - some free services - Store up to 2,000 subscribers & send up to 12,000 emails per month. Also these services will allow you to track your messages.
DavidF