Dovecot + Horde / Roundcube autoresponder with Plesk 12.5.27

[Paolo Gatti]

Hello, I have a debian 8 with Plesk 12.5.27.

I know that Plask 12.5.27 is not supported, but still I try to ask a question:
my customer need a vacation message, so I have configured a filter in Roundcube and/or a vacation message in Horde. configuration is ok, but not send any email. It seems that email is not sent. In log I don't have any interesting information.

Do you have a hint?

Thank you very much, Paolo.