Email previews show plain text version
If you are using phpList to send your email campaigns, you may run into an issue where Litmus shows a plain text version of your email, rather than the HTML version you want to test.
This is because phpList by default sends two copies of your email for testing purposes - one in HTML format, and one in plain text format. This is a useful feature, but can make it difficult to test your HTML version with Litmus.
To work around it, using phpList version 2.10.3 or later, you'll need to edit your phpList configuration file. This file is usually found in usr/public_html/lists/config/config.php.
You'll need to edit the line that reads:
define('SEND_ONE_TESTMAIL',0);
Changing it to read:
define('SEND_ONE_TESTMAIL',1);
You can find more information about editing your configuration file within the phpList documentation.