Plesk auto responder that was configured with SmarterMail does not work.
There are no any logs in Plesk and SmarterMail regarding any attempt to send an auto response.
Plesk mail filter was disabled on SmarterMail server.
Plesk does not use SmarterMail auto-reply feature, instead of this Plesk uses its own mail filter. If Plesk mail filter was disabled on SmarterMail server, auto-response will not work.
Enable Plesk mail filter in SmarterMail:
SmarterMail Administrator > Settings > General Settings > Spool Command-Line File > Enabled
Command-Line File should point to
%plesk_bin% folder. For example, Command-Line File string should looks alike:
C:\Program Files (x86)\Parallels\Plesk\admin\bin\smmailfilter.exe %filepath