Mailman/Postfix and the dreaded group mismatch

Bill Christensen billc_lists at
Thu Oct 7 11:08:27 PDT 2010

Hi folks,

I'm putting some of the final touches on my most recent server and 
have run into the dreaded Mailman group mismatch problem.

Before getting into that though, I'm curioius as to why MacPorts 
spreads the pieces of Mailman around to at least three different 
locations - /opt/local/var, /opt/local/share, and /opt/local/libexec 
- rather than in one convenient location as the 'normal' mailman 
installs do?  I can't see a whole lot of advantage to doing that 
besides confusing those of us who are transitioning from a 
non-MacPorts install.

Down to the problem.  We're running the latest OS 10.6 (client).  I'm 
using Fetchmail (MacPorts install) to retrieve the mail from the 3rd 
party server and deliver it to Mailman, and then sending out via the 
existing Postfix server.   The error I'm seeing when running 
Fetchmail is:

fetchmail: IMAP< A0008 OK Success
fetchmail: IMAP> A0009 FETCH 2 BODY.PEEK[TEXT]
Group mismatch error.  Mailman expected the mail
wrapper script to be executed as group "_mailman", but
the system's mail server executed the mail script as
group "staff".  Try tweaking the mail server to run the
script as group "_mailman", or re-run configure,
providing the command line option `--with-mail-gid=staff'.
fetchmail: IMAP< * 2 FETCH (BODY[TEXT] {25}
  (25 body octets) *

and though it appears that fetchmail is logging in correctly and 
seeing the mail there, it's not downloading to Mailman because of the 

I went into the Mailman portfile and added --with-mail-gid=staff to 
the configure, port uninstalled and reinstalled.  I'm still getting 
the same error.  Do I need to do something else to 'clean' the 
install of the old settings?

Or do any of you know what to change on the Postfix end in order to 
"tweak the mail server to run the script as group '_mailman'?

Thanks in advance.

Bill Christensen

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