While you could always configure Zimbra filters to send automated replies over CLI using:

/opt/zimbra/bin/zmmailbox -z -m account@domain.com afrl "Filter_name" active any address "to,cc" all is "alias@domain.com" reply "Auto reply message" stop

This feature was not available to the end user in the Web Interface. This Zimlet adds a button in Preferences -> Filters -> Create Filter to add this functionality.

The recommended method is to deploy using git.

# apt-get -y install git
# git clone https://github.com/Zimbra-Community/reply-by-filter.git
# cd reply-by-filter
# chmod +rx build.sh
# ./build.sh

Now we can deploy the generated tk_barrydegraaff_reply_by_filter.zip as any other zimlet.

Otherwise you can fetch an already built zip file from our reply-by-filter releases.

Only deployment in development mode is supported, this means it is enabled for all users and it cannot be configured via CoS settings:

  mkdir -p /opt/zimbra/zimlets-deployed/_dev/tk_barrydegraaff_reply_by_filter/
  wget https://raw.githubusercontent.com/Zimbra-Community/reply-by-filter/master/tk_barrydegraaff_reply_by_filter/tk_barrydegraaff_reply_by_filter.js -O /opt/zimbra/zimlets-deployed/_dev/tk_barrydegraaff_reply_by_filter/tk_barrydegraaff_reply_by_filter.js
  wget https://raw.githubusercontent.com/Zimbra-Community/reply-by-filter/master/tk_barrydegraaff_reply_by_filter/tk_barrydegraaff_reply_by_filter.xml -O /opt/zimbra/zimlets-deployed/_dev/tk_barrydegraaff_reply_by_filter/tk_barrydegraaff_reply_by_filter.xml

  rm -Rf /opt/zimbra/zimlets-deployed/_dev/tk_barrydegraaff_reply_by_filter

For now, filters that have a reply action will turn read-only after you save them, it is another build in limitation of Zimbra.