[Mailman-Users] Messages bounce but only for one domain on one list

[Tom Caudron]

I sent out a message about this over the weekend, but since the nature
of the problem changed (and I got no replies to the first post anyway)
I'm moving it to it's own thread for clarity.

I set up my Gentoo linux server with:

Postfix 2.0.16-r1
Mailman 2.1.4
Fetchmail 6.2.3

Once I got the setup all working (with the default Mailman list and 2
other lists) and I'd tested it, I set about adding the rest of the
lists.

When I added the next list, however, that new list didn't work right.

Apparently, I'm getting a 550 bounce error in
/var/log/mail/current, BUT only for one domain (happens to be the same
domain as the list is on), which means that subscribers on a different
domain are getting messages just fine.  No 550 bounce.  A sample error
follows:

Feb  9 08:33:27 [postfix/smtp] 6C30418B04: to=<username at mydomain.com>, relay=mx00.1and1.com[217.160.230.10], delay=0, status=bounced (host mx00.1and1.com[217.160.230.10] said: 550 rejected: unknown local-part in sender <mylist-bounces at mydomain.com> (in reply to MAIL FROM command))

So, for this one list (remember all the others work fine regardless of
domain), I need to tell it not to try to resolve the usernames locally
since it is not the mx for this or any domain.  Those users don't exist
on my server.

To be clear, say my list is MyList at MyDomain.com and I have two members
(User at Mydomain.com and User at AnotherDomain.com).  When a message is sent
to the list by either user, it is collected and added to the archive,
but only User at AnotherDomain.com will get the message in his inbox.  For
User at MyDomain.com I will get an error similar to the one I detail above
because it is trying to resolve all MyDomain.com address to local
users...but only for this one list!  The others appear to work fine.

Is there some setting I'm missing that overrides the
local_recipient_maps variable (found in /etc/postfix/main.cf) on a per
list basis?

In /etc/postfix/main.cf, I've set:

local_recipient_maps = 

Because setting it to nothing is postfix's way of telling itself not to
try to resolve names locally.  The default setting causes all mail sent
to external users to fail with the 550 bounce message in
/var/log/mail/current just as it is now for that one list.

I admit that I'm a little confused.  Anybody every run across this issue
before?  I'm sure it's just a simple config error on my part, but any
help at all would be appreciated.

-Tom Caudron