How do I block emails with certain words in subject in Mail Assure

Last Modified

Thu Sep 03 15:46 GMT 2020


  • How do I block emails with specific word in the subject?


  • N-able Mail Assure


  • Important: Block rules can have a large impact on mail flow. Rules should be thoroughly tested before being used in production. 
  • To configure blocking (handle as spam) of emails with certain words in the subject:
  1. At Admin level (before selecting a domain from Domains overview), In the menu structure: Incoming - Protection Settings,  select Blacklist Filtering Rules
  2. Select the navigation tab Domain Rules to apply the rule to a single domain, or Admin Rules to apply to all domains contained within the current admin account.
  3. Click on the Add Rule button
  4. Enter a descriptive Rule name, and a Priority number value. 
    • The priority value is to control the order in which filtering rules are applied.
  5. In Header name, enter Subject (case sensitive)
  6. Select Header from the dropdown Match menu
  7. In Regular Expression, enter (word1|word2|word3)
    • This is in standard Regular Expression (RegEx) format. The sample rule above will block all messages where the message headers for the Subject contain either word1 or word2 or word3 (multiple values will match, as the Subject does match).
    • Note: The rule will match all subjects which contain these words anywhere in the subject header.
  8. In Flags, enter i if you would like this rule to be case insensitive. Leave this blank for the rule to only apply to the exact case specified in the rule.
  9. Click Save
  • Note: The Technical Support team is unable to support any customisation of the predefined Rulesets or those you build yourself. Due to the potential complexity in building a regex pattern, we advise that only users with regex experience should attempt to create new rules or customise existing ones.