[SM-USERS] Unable to send to local users

[<1...@mo...>]

Hi,
I'm running the latest version (1.4.10a) of SQMail available on FreeBSD,
with Postfix & Courier IMAP handling the back-end stuff.   Some while ago it
became apparent that I could no longer use Webmail to send mail to local
users; remote users work fine.  There is no problem mailing local users
using the command-line mail, nor from a remote PC using POP/SMTP.  

Unfortunately I do not know what changes I made to cause this to stop
working as it took a while for me to notice.

Sending mail to e.g. local user us...@vi... from SQMail
us...@ot... results in a bounce to
Postmaster@main-server-domain, containing the error
"
   ----- Transcript of session follows -----
554 5.0.0 MX list for virtual-domain.com. points back to
main-server-domain.com
554 5.3.5 Local configuration error
"

There is also an entry in maillog:
"Oct 14 10:54:00 server-name sm-mta[27429]: l9EEs041027427: l9EEs041027429:
DSN: Local configuration error"


There is something in the archive about this, but I was unable to resolve my
problem using the information there.  Sendmail should not be running as it's
disabled in rc.conf; there should only be one MTA running on the machine, as
far as I know.

Does anyone have any suggestions where to go from here?

Thanks,
Mark