For us, this was resolved after we did a 'rpm -Uvh --force' for the 'sw-cp-server' package. Just in case someone runs into this again and the above instructions turn out to not be sufficient :-)
Ours was resolved by resetting the permissions on the mail handlers directory; the mail handlers base directory was only accessible to the root user, and several of the account subdirectories were missing some permissions as well.
Unclear what caused it, but it resolved the issue, and...
We have received reports from clients that they can no longer set up a working autoresponder. It shows in the panel interface, autoresponders are on, the appropriate autoresponder is activated as well, but there is no automatic response when tested.
We are able to replicate this problem...