opensense-docs/source/manual/how-tos/mailgateway.rst

=================================
How To: Setting Up A Mail Gateway
=================================

.. Warning::
    A mail gateway under high load may need a lot of memory and CPU power.
    Keep in mind that the components have some hardware requirements like the
    ClamAV- and the Redis plugin.
    It is not recommended to run this software on weak hardware.

------------
Installation
------------

First of all, you have to install the required plugins from the plugins view.

.. image:: ../images/menu_plugins.png

The required plugins are:

* ClamAV
* Postfix
* Redis
* Rspamd

After a page reload you will get some new menu entry under services for all installed plugins.

----------------------------
Configuration Of The Plugins
----------------------------

1. ClamAV
---------

For ClamAV, you can follow the instructions in :doc:`clamav`.

2. Redis (optional but recommended)
-----------------------------------

In the next step, we need to install the Redis database. Redis is required for caching and for
some features of the rspamd plugin.

.. Warning::
    If you don't set up a Redis instance, some components of rspamd will automatically disable
    themself silently and it will not be visible in the GUI.

.. Image:: images/redis_general.png

For a basic Redis instance, you can just check `Enable Redis` and click `Apply` to start the servers.


3. Rspamd
---------

First of all, you will need to activate the plugin by checking the `Enable rspamd` checkbox.
If you have installed and configured the Redis plugin, you should check the second checkbox as well.

.. Image:: images/rspamd_general.png

If you are ready, rspamd should be up and running.

Now you should configure the rspamd modules you need.

.. Note::
    The ClamAV component does enable or disable itself automatically if it has been configured
    depending on the ClamAV (clamd) configuration.

For example, if the MX should be checked, the menu for the `Spam Protection`:

.. Image:: images/rspamd_antispam_menu.png

After a click, you will see the form:

.. Image:: images/rspamd_mx_check.png

In this case the configuration is quite simple: Check `Enabled`, add a cache expiration time (in
Seconds) as well as clicking at the `Apply` button.

Postfix
-------

First of all, you need to configure the domains you want to forward in the `Domains` menu.
.. Image:: images/postfix_add_new_domain.png

Enter the values for your mail server in the dialog after clicking `+`:

.. Image:: images/postfix_add_domain_forward.png

After saving usually the apply button needs to be hit but the server is not running anyway as it
needs to be configured first. If you add new domains, you have to hit this button to apply changes.

.. Image:: images/postfix_general_tab.png

In the `General` tab, the Postfix service must be enabled.
If your system settings differ from your system settings, you may override them here.
For example overriding the hostname makes sense because you may want to use the hostname
which has been configured as the MX host in the DNS.

You shhould keep the checkboxes at the bottom enabled as they enable restrictions, which provide an additional layer of security.

Save the changes and switch to `Antispam` tab.

.. Image:: images/postfix_antispam_tab.png

Enable the Checkbox and click `Save`.

---------------
Follow Up Tasks
---------------

In the next step, you should go to the `Firewall` menu.
Create a new rule to pass port TCP/25 traffic from `Any` to `This Firewall`.