This option enables you to add a suffix of parameters to the end of the preview URL this can be useful if you need to handle preview in a special way.

Example of usage in the config.php file

$mcImageManagerConfig['preview.urlsuffix'] = "?someparam=somevalue";

Example of usage in the Web.Config file

<add key="preview.urlsuffix" value="?someparam=somevalue" />

Example of usage in a mc_access file