If you have an existing HTML element that you wish to insert into your emails in Prospectreach, then you can do it by using the Source code box. 

When you create or edit a campaign, go to Step 2 and find the email in which you want to place the code into.

Click the View menu bar to open it up, then select Source code.

This will open up the Source Code box. In the Source code box, you can place your HTML code for the email. Below is an example:

After hitting Ok, this is how it shows in the email:

This also works for videos from video hosting sites (Youtube, Vimeo, etc.) that you want to insert into your email.