Help & How-to

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.

 

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, and when the score is higher to the pre-set value (see Antispam) it is added the following header
"X-Spam-Virus: yes"
In order to indentify spam you can use this value in your custom Sieve filter.

 

 


Identifying emails with attachment

when an email has an attachment, the header "X-Attach" is added . For example the following rule identifies email with attachments.

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


How to block spam at "server" level

It is possible to block spam at "server-side" without emails hit your email box. The following rule performs this action

["Header"] ["X-Spam_bar"] [contains] [+++++++++++++++++++++++++]

The number of "+" is in funtion of the spam-score the email needs to have to trigger the rule. 

For example:

X-Spam_score: 31.3
X-Spam_score_int: 313
X-Spam_bar: +++++++++++++++++++++++++++++++

 

 

 

 

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