Email module transition to Rspamd¶

Since NethServer Enterprise 7.5.1804 new Email, Connectors and POP3 proxy installations are based on the Rspamd 1 filter engine.

Previous NethServer Enterprise installations are automatically upgraded to Rspamd as described by this section.
New configuration features, specific to the Rspamd-based implementation, are documented in Email. Here is a brief list:
- DKIM signature
- Rspamd web UI
- Greylist threshold 3

Feature changes¶

Append a legal notice¶

The Email > Domains > Append a legal note to sent messages (also known as "Disclaimer") feature was split in a separate, optional package: nethserver-mail2-disclaimer. New installations should avoid it, as it relies on an old package 4 that can be removed in future releases.

Block port 25¶

The block of port 25 can prevent abuse/misuse by LAN machines. If the system is acting as the LAN network gateway, the administrator can create a firewall rule inside the Rules page.

Additional host name aliases¶

The following host name aliases were automatically registered in the local DNS service, if the postfix/MxRecordStatus was enabled:

smtp.<domain>
imap.<domain>
pop.<domain>
pop3.<domain>

When upgraded from an old Email module based on Amavisd, the postfix/MxRecordStatus is removed and those aliases are pushed as self records in the hosts DB. They can be edited from DNS > Server alias page.

MX record for LAN clients¶

The new Email module implementation based on Rspamd does not push the MX record override for LAN hosts any more. Ensure the LAN mail user agents are configured to use SMTP/AUTH or are listed in Email > SMTP access > Allow relay from IP addresses before upgrading.

Upgrade procedures¶

Manual upgrade procedures are no longer needed: upgrade occurs automatically.

References

1: Rspamd -- Fast, free and open-source spam filtering system. https://rspamd.com/
2: Domain Keys Identified Mail (DKIM) is an email authentication method designed to detect email spoofing -- Wikipedia
3: Greylisting is a method of defending e-mail users against spam. A mail transfer agent (MTA) using greylisting will "temporarily reject" any email from a sender it does not recognize -- Wikipedia
4: alterMIME is a small program which is used to alter your mime-encoded mailpack -- https://pldaniels.com/altermime/