HREF link code in Contribution page footer causes HTML validation error

This code existed already for a site in the 'footer' section of Title and Settings for a Contribution Page. They were trying to save something else, like a title change.

<BR>If you experience any difficulties making a contribution, please email <a href="mailto:info@unifem-usnc.org">info@unifem-usnc.org</a>. Thank you.

This simple code produces a HTML validation ("suspicious") error when attempting to save. Causes great confusion for users when they cannot save pages that have been working for over a year. Remove the HTML HREF link and it works.