Server-side Mail Filtering

Our email system supports Sieve e-mail filtering. You can apply filters for incoming e-mail messages as though they are delivered to a specific directory in your emalbox.
If you like to structure emails based on the sender/to/cc/subject into dedicated folders then you can create Sieve Filters for that purpose.
The Sieve scripts can be generated by a GUI-based rules editor using squirrelmail.
squirrel client
Spamassassin
When an emailbox uses Sieve Filter the spam is not moved in the Junk folder automatically.
To identify spam from Spamassassin you need to add the following rule

["Header"] ["X-Spam_score"] ["Matches wildcar"] ["*"]

The header "X-Spam_score"  will be added only when the "spam score" is above the spam-threshold (https://www.servermx.com/en/help/howto/antispam.html)


ClamAV antivirus
Incoming emails are checked against virus with ClamAV. ClamAV is a tool-kit able to detect many types of malicious software, including viruses.
When an email contains a virus ClamAV with spamassassin indentify the email as spam an when the score is higher to the pre-set value (see Antispam) is add the following header
"X-Spam-Virus: yes"
In order to indentify spam you can use this value in your custom Sieve filter.
squirrel filter


Identifying emails with attachment

A special header id added in case the email has an attach. The header is" X-Attach:yes". For example the following rule identifies email with attachments.

["Header"] ["X-Attach"] [contains] [yes]