HI One week ago I shifted from Qmail to Zimbra Open Source Edition.Earlier my Qmail server was hving 2 domains abc.com and xyz.com ...but I have not shutdown the services on Qmail server that server is as it is ..what I did just increase the MX record for my Qmail server.Most of the Emails are receiving by Zimbra Server but some of the emails are receiving by Qmail.

It seems that those emails with unknown host are not receiving by zimbra.I have already uncheck the unknoewn host option in zimbra administration knosole.
Can any one help me out .Where I am wrong....