Failed to send Emails after updating


We urgently need your support.

After updating to version 7.4.3 we cannot send emails.

After clicking to end button, we get an very long popup-window with

warning-messages like this:

Cannot retrieve value of undefined directive Core.DisableExcludes invoked on line 19453 in file

… /include/HTMLPurifier/HTMLPurifier.standalone.php
in … /include/HTMLPurifier/HTMLPurifier.standalone.php on line 2607[/size]

Please help.
This seems to be a bug in the new version.

Thank you !