[Mailman-Users] need help

[RoB-O]

i have installed mailman  and everything seems to work up to the point
that when i try to subscribe to the list, when replying to join  i
receve this error message

  ----- The following addresses had permanent fatal errors -----
> "|/home/mailman/mail/wrapper mailcmd webopps"
>     (expanded from: <webopps-request at listserv.ath.cx>)
>
>    ----- Transcript of session follows -----
> sh: wrapper not available for sendmail programs
> 554 "|/home/mailman/mail/wrapper mailcmd webopps"... Service
unavailable
>

i have checked sendmail and it shows the users for the mailman
groups......
please help!