Mail Security and catch all account


We are planning to implement Email Security on our domain but we have a question.

We have a specific mailbox on our 365 Exchange that acts as a "catch-all" account. So it receives email from any address that does not exist on our domain ([email protected] gets delivered to catcha[email protected] for example, when the mailbox xyz does not exist).

How would mail security handle this, since we have to add mailboxes to be managed to the console?

Would those emails still be delivered? The rules that cause this behaviour are on the exchange server which would be behind Mail Security.

Thank you.



  • Gjoksi
    Gjoksi DEFENDER OF THE YEAR 2022 ✭✭✭✭✭
    edited September 2022


    Since you need help with business product, @Alex_Dr or @Andra_B could take a look here and help you with the issue.

    Also, you can always contact the Bitdefender business support:


  • Andra_B
    Andra_B Customer Experience Projects Manager BD Staff

    Hi @AFLemos

    First, I want to apologize for the delay.

    In order to configure catch-add addresses in Email Security, you should follow the steps below:

    1.  Go into Connection Rules, enable View System Rules.
    2. Turn Off DHA rule.
    3. Go into Message Rules, create a new rule with the following content:
      1. Selected Conditions => Mailbox Exists - Matches - False
      2. Selected Conditions => Direction - Matches - Inbound
      3. Selected actions => Re-Route to - "catch-all-address-name@%RpctToDomain%"
      4. Eg. to reroute all mail for * to the mailbox [email protected], use the string: john@%RpctToDomain%
      5.      This will match the recipient domain (right of @) and keep it unchanged (%RpctToDomain%) and only rewrite the mailbox name (left of @) from whatever it was named to john@
      6. Give the rule a name, save it and move it to the first position in the Message rules list
    4. Done.

    Please let me know, how it worked.