Email 2 (Beta)

The Email 2 module is an alternative to Email, based on the Rspamd filter engine. It aims to be the successor of the current Email module, by providing the same old features plus new ones. For background information refer to the Email chapter.

Once installed from the Software center page, go to the Email page as usual.

This new module provides the email filter engine for the POP3 connector and POP3 proxy modules too, therefore an upgrade for those modules is required. See Upgrade procedures.

Features planned for final release

  • Backward-compatible disclaimer signature (on development)
  • Integrate Rspamd UI in Server Manager (waiting for an upstream fix)

Configuration options

New configuration options, specific to Email 2, are

  • DKIM signature
  • Rspamd web UI
  • Delay for suspicious threshold (greylisting)

DKIM signature

DomainKeys Identified Mail (DKIM) provides a way to validate the sending MTA, which adds a cryptographic signature to the outbound message MIME headers.

To enable the DKIM signature for a mail domain, enable Email > Domains > Sign outbound messages with DomainKeys Identified Mail (DKIM).

To work effectively, the public DNS must be configured properly. Follow the instructions provided by the configuration page itself.

The DKIM signature headers are added only to messages sent through TCP ports 587 (submission) and 465 (smtps).

Rspamd web UI

The Rspamd web UI is available on a randomized URL via the administrative HTTPS port 980 (like Server Manager). For security reasons the connection is restricted to trusted networks only.

The random URL and the password required to access Rspamd web UI are available under Email > Filter > Rspamd user interface.

The URL is also available listed under the Applications page.

Delay for suspicious threshold

A new spam score threshold is provided by Rspamd. If the spam score is above it, the message is temporarily rejected. An SMTP-compliant MTA must attempt to deliver the deferred message again; spammers are likely to give up instead.

To adjust the threshold see Email > Filter > Anti spam > Delay for suspicious threshold.

Upgrade procedures

It is possible to switch a running system to this new module, starting from the Email module, SMTP proxy or POP3 connector module.

If something is wrong with rspamd, please report the issue on community.nethserver.org.

To switch an old mail server with amavisd-new filter engine to rspamd run the upgrade commands reported on the following sections. It is possible to revert the upgrade too.

From Email module

Upgrade:

yum swap \
    -- remove nethserver-mail-{common,filter,server} \
    -- install nethserver-mail2-{common,filter,server}

Revert upgrade:

yum swap \
    -- install nethserver-mail-{common,filter,server} \
    -- remove nethserver-mail2-{common,filter,server}

From SMTP proxy module

Upgrade:

yum swap \
    -- remove nethserver-mail-{common,filter} \
    -- install nethserver-mail2-{common,filter}

Revert upgrade:

yum swap \
    -- install nethserver-mail-{common,filter} \
    -- remove nethserver-mail2-{common,filter}

From POP3 connector module

When upgrading to Email 2, the POP3 connector settings of each account regarding Check messages for SPAM and Check messages for virus options are ignored and overridden by the new Scan messages with email filter.

Upgrade:

yum swap \
    -- remove nethserver-mail-{common,filter,server} nethserver-getmail nethserver-spamd \
    -- install nethserver-mail2-{common,filter,server,getmail}

Revert upgrade:

yum swap \
    -- install nethserver-mail-{common,filter,server} nethserver-getmail \
    -- remove nethserver-mail2-{common,filter,server,getmail}

From POP3 proxy module

Upgrade:

yum swap \
    -- remove nethserver-mail-{common,filter} nethserver-p3scan nethserver-spamd \
    -- install nethserver-mail2-{common,filter,p3scan}

Revert upgrade:

yum swap \
    -- install nethserver-mail-{common,filter} nethserver-p3scan nethserver-spamd \
    -- remove nethserver-mail2-{common,filter,p3scan}