Good day! Go to excuse my English) in the general problem is the server installed Zimbra Opensource and there is a problem at all to pile Zimbra desktop but since in Desktop features no confirmation of delivery, I decided to implement with postfix read the manual and found it seemed to me then what I need. Add a line in /opt/Zimbra/postfix/conf/
smtpd_discard_ehlo_keyword_address_maps = cidr: /etc/postfix/ esmtp_access
ordered online go to restart the server
send the command sendmail-N success and in response to the silence as if sendmail is waiting for the completion of the line.
And accordingly no reports about what that something was delivered to no.
Thank you.