This may be caused by the HTML used in the email.  Small modifications to the HTML may allow the links to work.

Disclaimer: Blackbaud provides programming examples for illustration only without warranty either expressed or implied including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes you are familiar with HTML/CSS/JavaScript and the tools used to create and modify this code. Blackbaud Customer Support may help explain where the code should live in the product, but we will not modify or assist you with modifying or troubleshooting these examples.

Please contact your account manager to discuss a billable service with our Professional Services team to discuss resolving the links within the email. 

Additional Information
Email Formatting in Microsoft Outlook
Content in email displays differently when using different email clients