Description

The Email Experience Manager (EXM) might duplicate the base URL if an internal link is sent within a Simple HTML Message email. For example:

1. A user creates a message based on the Simple HTML Message template, adds an internal link to the message, such as:

   http://test.com

   and sends the current message.
2. A recipient clicks on the link.
3. EXM resolves the click action and redirects the user to:

   http://test.com/://test.com

Solution

To resolve the issue, download and install the patch compatible with the affected product version found on this page:
https://github.com/SitecoreSupport/Sitecore.Support.208586/releases.

The issue is not reproducible in Sitecore XP 9.3 Initial Release and higher versions as the Simple HTML Message template has been removed.