AddToCalendar.com gets invalid event parameters

[MatthewHickman]

Good morning, I am trying to embed addtocalendar inside of a Drupal page unfortunately I am receiving the following error:

AddToCalendar.com gets invalid event parameters
Sorry, but the provider of the event sends wrong parameters of the event and we can't create a valid response. We'll contact event provider and fix the error. You can leave your email and we will send you information about the event as soon as everything is fixed:

Here is the error log:

This value is not a valid email address.Passed value: <a href="mailto:myemail@myclient.com" class="mailto">myemail@myclient.com<span class="mailto"><span class="element-invisible"> (link sends e-mail)</span></span></a>

However, when I copy and paste the exact same code into a text file and run in my browser everything works exactly as it should.

Any ideas on why this could be occuring? Any ideas on how I can fix it?