VNC Disclaimer Middleware Installation and Setup

The VNC Disclaimer Middleware is provided as debian package (deb) for Ubuntu 22.04 distributions in a gitea repository, maintained by VNC.

It is plugged into the Zimbra MTA using the milter protocol.
Upon startup it reads distribution lists and member accounts from the Zimbra LDAP and caches the information. The cached information is refreshed in a configurable interval with a default value of 10 minutes.
When an eMail is processed using this milter, these following actions are performed:

determine the distribution-list membership of the sender
add the respective disclaimer according to the configuration in the corresponding format (plain text/ html) to the end of the eMail, but only if the desired disclaimer has not been added to the eMail conversation yet, e.g. if replying to an eMail that already contains a disclaimer.

Prequesites

Gather system information

In order to setup the VNC Disclaimer Middleware for your Zimbra environment, the following information, queried as user zimbra via CLI, is required.

Zimbra LDAP URL

  zimbra@zcs:~$ zmlocalconfig ldap_url
  ldap_url = ldap://zim.nowhere.org:389
  zimbra@zcs:~$

Zimbra LDAP credentials

  zimbra@zcs:~$ zmlocalconfig -s zimbra_ldap_password
  zimbra_ldap_password = MyLDAPpw
  zimbra@zcs:~$

Requirements for the VNC Disclaimer Middleware host

required OS: Ubuntu 22.04
the machine must be able to resolve the hostname of the Zimbra LDAP node via distributions
access to an account profile with sudo permissions

Installation

setup the software repository for the VNC Disclaimer Middleware installation using an account with sudo permissions.

  sudo curl https://repos.vnc.de/api/packages/primerica/debian/repository.key -o /etc/apt/keyrings/gitea-primerica.asc
  echo "deb [signed-by=/etc/apt/keyrings/gitea-primerica.asc] https://repos.vnc.de/api/packages/primerica/debian jammy main" | sudo tee -a /etc/apt/sources.list.d/gitea.list
  sudo apt update

install the VNC Disclaimer Middleware via apt
```
  sudo apt install vnc-disclaimer
```

Setup & configuration

adjust mandatory parameters in configuration file /etc/vncdisclaimer/clouddird.cf using the information gathered from the Zimbra LDAP before and replace the values accordingly:
```
  # Zimbra LDAP URI
  disclaimer-ldap-uri=ldap://zim.nowhere.org:389

  # Zimbra LDAP bind password
  disclaimer-ldap-password=MyLDAPpw
```

!!!tip "If parameters are no set in /etc/vncdisclaimer/clouddird.cf their default values are used."

Optional configuration parameters and their default values

In addition to the two LDAP config parameters, that are mandatory and have to be configured for your environment, there are optional config parameters to adjust as well.

Parameters and their default values (if unset):

Config Parameter	Description	Default value
disclaimer-directory	absolute path to the directory containing the mail disclaimer files	/etc/vncdisclaimer/disclaimers/
disclaimer-ldap-bind-dn	Zimbra LDAP bind dn (uid=zimbra,cn=admins,cn=zimbra)	zimbra,cn=admins,cn=zimbra
disclaimer-milter-port	ip port to bind for the disclaimer milter service	9001
threadpool-size	maximum number of parallel tasks	20
disclaimer-cache-seconds	number of seconds to cache disclaimer files and Zimbra distribution lists	600
disclaimer-charset	character set to read the disclaimer files with, see https://docs.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html for supported values	UTF-8
disclaimer-exceptions-file	file name of the list containing the sender addresses that should be excluded from disclaimer processing, relative to the directory location of this config file (clouddird.cf)	disclaimer-exceptions.txt
debug	enable debug mode for more verbose logging	off

Setup disclaimers

The disclaimer have to be created in /etc/vncdisclaimer/disclaimers/ if nothing else is provided in clouddird.cf. A few examples are provided for plain-text and HTML version for disclaimer in the directory after the installation already.
The naming the convention for the disclaimer files has to follow this scheme:

    <distributionlist-address>.<type>

where,

distributionlist-address is the eMail-address of the respective Zimbra distribution-list, where the senders, that should have the content of this file attached as disclaimer to the eMails they send, need to be members of
type is either txt for plain text or html for HTML mail parts.

Note: "all disclaimer files have to be encoded in UTF-8 and use LF only as newline character (standard unix format, see https://en.wikipedia.org/wiki/Newline ), in doubt, please use dos2unix to convert the files"

Finally start the VNC Disclaimer Middleware service:
```
  sudo systemctl status vncmilter
```
To apply any change performed to the configuration, the vncmilter service needs to be restarted:
```
  sudo systemctl restart vncmilter
```

Zimbra MTA Integration

Log into the CLI of each Zimbra MTA node of your Zimbra Collaboration Suite installation via ssh, become user zimbra and

set zimbraMilterServerEnabled to TRUE

  zimbra@zcs:~$ zmprov ms `zmhostname` zimbraMilterServerEnabled TRUE

add the VNC Disclaimer Middleware to your configuration, using the IP of your VNC disclaimer middleware server (in this example 192.168.21.42 is used):
```
  zimbra@zcs:~$ zmprov ms `zmhostname` zimbraMtaSmtpdMilters "inet:192.168.21.42:9001"
```

restart the MTA services to apply the changes:

  zimbra@zcs:~$ zmmtactl restart && zmprov fc all

Now all eMails are processed by the VNC Middleware service.

Miscellaneous

all account listed in the disclaimer-exceptions-file (default location: /etc/vncdisclaimer/disclaimer-exceptions.txt) will not get any disclaimers attached to their eMails up on sending.
all Zimbra accounts that are not listed in the disclaimer-exceptions-file and are not members of a distribution list, where the name convention reflects a disclaimer file in /etc/vncdisclaimer/disclaimers/, will get the default disclaimer setup in /etc/vncdisclaimer/disclaimers/default.html(.txt) attached to their eMails up on sending.
in case an account is member in multiple distribution-lists, that each have disclaimer configursation files setup for their names, all the suiting disclaimers according to the account's membership will be added to the account's eMails up on sending