New to zimbra.

Currently I have 2 servers, my production mail server is sendmail/dovecot with about 200 users on it. It has openwebmail as a webgui.

I loaded up the VMware version of zimbra on a second server. I would like test out Zimbra with 20 of my users.

Is there a way to keep my production server with 180 accounts active and working and have 20 accounts on zimbra active and working.

I was thinking if I have my production server as Zimbra's upstream mail server this could work but I thought there might be a better way to do this.

Also just a curiosity question, is anyone running the VMware version in production?