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Version: 1.1

Message count based on sender

This condition lets you filter messages based on how many messages a matching sender has sent within a time interval. This is useful for detecting mass mailing, throttling overly active senders, or spotting compromised accounts that suddenly start sending large volumes of mail.

The Message count based on sender dialog, with match by email address, user, group or domain, a comparison, a count and an interval

Sender match by​

Choose which senders are counted:

Email address​

Enter the sender's email address and choose how to match it:

  • Exact match - The email address must match exactly (e.g. john@mshsoftware.com)
  • Wildcards - Use * to match patterns (e.g., *@mshsoftware.com matches anyone from that domain)
  • Regular expression - Use advanced pattern matching for complex rules

You can enter multiple addresses or patterns separated with ; (no spaces).

User​

Select a specific user from the list. Only messages sent by that user are counted.

In Group​

Choose a group from the list. Messages are counted when the sender belongs to that group.

In Domain​

Select a domain. Messages are counted when the sender's email address belongs to that domain.

Comparison​

Set how to compare the message count:

  • Equal - Exactly matches the number you specify
  • Not equal - Any count except the number you specify
  • Greater than - More messages than the specified number
  • Greater or equal - At least the specified number of messages
  • Less than - Fewer messages than the specified number
  • Less or equal - No more than the specified number of messages

Count​

Number of messages to compare against.

Interval​

The time window the messages are counted in, for example the last hour. The condition looks at how many matching messages were sent within this interval and compares that number against the count.

Additional resources​