Detecting the use of BCC from the content filter

This is a simple content filter rule that will help you in filtering messages where the current destination was BCC’d rather then being listed in the TO or CC field.

Note that this will trip on most mailing lists — This is correct behaviour, unless the mailing list fills in the recipient’s name in the TO field (and most do not), lists are essentially using BCC.

It only works reliably in the LocalQ, it won’t work in the RemoteQ unless you turn off smartspooling, and it only works for mail received via SMTP, not MultiPOP or DomainPOP.

RuleName=Detect BCC’d messages
Condition01=TO|does not contain|AND|$HEADER:X-Rcpt-To$|
Condition02=CC|does not contain|AND|$HEADER:X-Rcpt-To$|
Action01=add header|”X-BCC”,”True”

To use this rule, copy the above text and paste it into the very top or very bottom of your MDaemonAppcfrules.dat file using Notepad, then open the content filter dialog in MDaemon and enable the rule.

No semaphore files needed, no need to restart MDaemon.

CC BY-NC-ND 4.0 Detecting the use of BCC from the content filter by Dave Warren ( is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

6 Replies to “Detecting the use of BCC from the content filter”

  1. Hi there,

    I need to content filter incoming mail that are BCC to a public folder.

    Following your instruction,
    I cannot find MDaemonAppcfrules.dat file or Appcfules.dat.

    We are using Mdeamon Version 9.55

    Please help if you got time and thank in advance.

  2. hello
    this system works, but i am able to trap the mail coming in as Bcc, and not going out as Bcc

    how can i trap the mails going out as Bcc

  3. i have not received bbc email through mdaemon. please provide the solution about this issue.
    how to received bbc mail in outlook through mdaemon.

  4. Hello,
    I need to do the following, could you please help with a solution, would truly appreciate.

    1) Either Content Filter normal emails (not lists) in which there is being marked a copy as BCC, to a given email id in the domain.

    2) Allow or Disallow users to use “Advanced Compose” section while they use worldclient, so they cannot send an email where BCC is marked.

    I would truly appreciate your guidance in this. Please note I’m only refering to general emails being sent out of office and not any list


  5. i need content filter for spam that my users is receiving. the spammer put mail in bcc and i receive message like ‘undisclosed-recipients:’ in ‘To’ of my message header.

  6. As a rule, BCC based filtering has almost no impact on spam filtering.

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