Block members from sending cc's and bcc's

Hi everyone,
Using Mailman 3 with Affinity web interface and we want to stop our members from sending to cc: or bcc:
We've found the Header Filter and cc and bcc appear in it. Tried to configure it to "hold for moderation," but it hasn't worked. Partly because we don't understand what to put in the Pattern input box. I put in cc: because it requires something.
Can anyone advise?
Cheers, Cathryn

On 6/23/25 10:04, Cathryn McGuire wrote:
Using Mailman 3 with Affinity web interface and we want to stop our members from sending to cc: or bcc:
We've found the Header Filter and cc and bcc appear in it. Tried to configure it to "hold for moderation," but it hasn't worked. Partly because we don't understand what to put in the Pattern input box. I put in cc: because it requires something.
The pattern box contains a regular expression that matches the value in
the header that you want to apply the action to. What you want is a
pattern that matches anything, e.g., .*
to match zero or more
occurrences of any character.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan

What you want is a pattern that matches anything, e.g., .* to match zero or more
occurrences of any character.
Please confirm that setting up a rule for cc's in Header Filter to "hold for moderation," it should block the member from sending a cc?
And, for the pattern, are you suggesting I use ".*" with cc: as the regexprs? Or, what exactly do I use under as a regular expression? Cathryn

Please confirm that setting up a rule for cc's in Header Filter to "hold for moderation," it should block the member from sending a cc?
It will hold for moderation any message containing a Cc: header. It won't prevent the moderator from accepting the message.
And, for the pattern, are you suggesting I use ".*" with cc: as the regexprs? Or, what exactly do I use under as a regular expression?
Use cc as the header and the two characters .* as the pattern (or whatever affinity calls it). See https://docs.python.org/3/library/re.html for information about Python regular expressions.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan

On 6/23/25 10:04, Cathryn McGuire wrote:
Hi everyone,
Using Mailman 3 with Affinity web interface and we want to stop our members from sending to cc: or bcc:
You won't ever see a Bcc: header in mail to a list. The whole point of Bcc: is to not expose the additional recipients or the fact that there were additional recipients so the sending MUA includes the Bcc recipients in the SMTP RCPT TO commands, but drops the Bcc: header from the message.
I.e., There is no way to know whether the original sender included Bcc: recipients or not.
-- Mark Sapiro <mark@msapiro.net> The highway is for gamblers, San Francisco Bay Area, California better use your sense - B. Dylan
participants (2)
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Cathryn McGuire
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Mark Sapiro