[Mailman-Users] you are not allowed to post

[bart]

Hi
I am newbe in mailman subject.
I had no problem to install mailman it went smooth and nice.
After successful instalation I opened web interface > Membership
Management... > Mass Subscription  and I added a few email adresses.
Each of them received  "Welcome to the "trip" mailing list" email

"
To post to this list, send your email to:

  trip at myserver.ltd
"

So it looks like everything is ok but if I try to send post to the
list my email is bounced with following messsage

You are not allowed to post to this mailing list, and your message has
been automatically rejected.  If you think that your messages are
being rejected in error, contact the mailing list owner at
mailman-owner at myserver.ltd

any idea what i did wrong?