hi..
i'v create 3 distributions list name All, TeamA, SubTeam. All these distribution list got their own users...

for All dist. list, it is a main dist list which is TeamA and SubTeam are include in the dist list.
for TeamA, SubTeam is include in this dist list...

when i sent email to All dist list, i got undelivery email like this:

This is the mail system at host mydomain.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<TeamA@mydomain.com>: host mydomain.com[10.xx.xx.20] said: 550 5.1.1
No such user here (in reply to RCPT TO command)

<subTeam@mydomain.com>: host mydomain.com[10.xx.xx.20] said: 550 5.1.1
No such user here (in reply to RCPT TO command)


how i do fix this error?
hope somebody can help me to solve this issue..