[Mailman-Users] Relay access denied

[Jardar Eggesbø Abrahamsen]

I have postfix on my server ludde.example.tld
I can send mail from jardar at externalserver.tld to jardar at example.tld
I can send mail from jardar at example.tld to jardar at example.tld
An example of the latter is this:

     Feb 17 14:01:11 ludde postfix/smtpd[18398]: connect from 
     localhost[127.0.0.1]
     Feb 17 14:01:11 ludde postfix/smtpd[18398]: 2AF0D109: 
     client=localhost[127.0.0.1]
     Feb 17 14:01:11 ludde postfix/pickup[18338]: 2BD18F9FB: uid=1000 
     from=<jardar at example.tld>
     Feb 17 14:01:11 ludde postfix/cleanup[18384]: 2BD18F9FB: 
     message-id=<Pine.LNX.4.62.0502171401030.18055 at ludde.example.tld>
     Feb 17 14:01:11 ludde postfix/smtpd[18398]: disconnect from 
     localhost[127.0.0.1]Feb 17 14:01:11 ludde postfix/qmgr[18339]: 2BD18F9FB: 
     from=<jardar at example.tld>, size=616, nrcpt=1 (queue active)
     Feb 17 14:01:11 ludde postfix/local[18385]: 2BD18F9FB: 
     to=<jardar at example.tld>, relay=local, delay=0, status=sent (delivered to 
     mailbox)
     Feb 17 14:01:11 ludde postfix/qmgr[18339]: 2BD18F9FB: removed

But when I try to join my mailman testlist, the maillog says:

     Feb 17 14:04:13 ludde postfix/smtpd[18468]: connect from 
     localhost[127.0.0.1]
     Feb 17 14:04:13 ludde postfix/smtpd[18468]: NOQUEUE: reject: RCPT from 
     localhost[127.0.0.1]: 554 <jardar at externalserver.tld>: Relay access 
     denied; from=<testliste-bounces at example.tld> 
     to=<jardar at externalserver.tld> proto=ESMTP helo=<ludde.example.tld>

Why?

Jardar