[Mailman-Users] mailman-to-postfix.py Illegal Invocationerrorswhen i put the correct transport

Mark Sapiro mark at msapiro.net
Thu Sep 15 16:35:57 CEST 2011

Paul Weinx wrote:
>Now I find another error when i post to a list, doesn't matter if to
>mailman at lists.domain.com or  mailman at domain.com, and I dare not change
>permissions without your advice:
>Sep 14 18:38:43 ws Mailman mail-wrapper: Group mismatch error.  Mailman
>expected the mail#012wrapper script to be executed as group "daemon",
>but#012the system's mail server executed the mail script as#012group
>"mailman".  Try tweaking the mail server to run the#012script as group
>"daemon", or re-run configure, #012providing the command line option
>Sep 14 18:38:43 ws postfix/pipe[29466]: E3CB03029A1:
>to=<mailman at lists.domain.com>, relay=mailman, delay=0.54,
>delays=0.49/0/0/0.04, dsn=5.3.0, status=bounced (Command died with status 2:
>"/usr/lib/mailman/bin/postfix-to-mailman.py". Command output: Group mismatch
>error.  Mailman expected the mail wrapper script to be executed as group
>"daemon", but the system's mail server executed the mail script as group
>"mailman".  Try tweaking the mail server to run the script as group
>"daemon", or re-run configure,  providing the command line option
>`--with-mail-gid=mailman'. )

Once again, please see the FAQ at <http://wiki.list.org/x/OIDD>.

The particular error you are seeing is a group mismatch error as
discussed in the FAQ at <http://wiki.list.org/x/tYA9>.

>What can i do? It sounds me not as easy as execute a simple chown... I also
>don't understand what's postfix-to-mailman.py pretending to do, if i don't
>want this script be executed, i want a pure integration.

To fix this error, yo need to either make the mail wrapper ecpect group
'mailman' or you have to make Postfix run the wrapper as group
'daemon'. Making the mail wrapper ecpect group 'mailman' is probably
the better solution, but I don't know how to do this in a
Debian/Ubuntu package (Again, see the FAQ at
<http://wiki.list.org/x/OIDD>). In order to make Postfix run the
wrapper as group 'daemon', look at master.cf. If you have something

mailman unix  -       n       n       -       -       pipe
  flags=FR user=mailman:mailman 
  argv=/usr/lib/mailman/bin/postfix-to-mailman.py ${nexthop} ${user}

you can change the user= to 'user=mailman:daemon' or
'user=daemon:daemon'. Either one should work.

>What will certainly get my attention, is that even though I came out I
>posted that bug you, simply by mydestinations = $ mydomain, the list worked
>perfectly! (sending to mailman at domain.com, what i want, cause i don't want
>to need to include the lists preffix). But with the exception that virtual
>users will not receive mail due to error "do not specify domain.com in BOTH
>mydestination and virtual_mailbox_domain" but I can not afford it because
>virtual users should be able to continue sending and receiving.

If you want to address your list mail to LIST at domain.com and not
LIST at lists.domain.com and you have user addresses that aren't lists
@domain.com, postfix_to_mailman.py is not the appropriate delivery
method; it is designed to work with dedicated domains. You should
remove the 'mailman' transport entries from the /etc/mailman/transport
file or remove any reference to it from transport_maps in main.cf, and
you should configure Postfix - Mailman configuration as described at
However, if you do this, you will need to fix group mismatch errors by
making the wrapper expect group 'mailman', and I can't tell you how to
do that in a Debian/Ubuntu package.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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