Creating a send-only user without mailbox
I'm currently planning a migration from a Postfix+Cyrus server to Zimbra (ZCS 8 NE). In our current setup we have a special user called mailrelay which can authenticate to Postfix in order to send mail, but which does not have a mailbox in Cyrus. This mailrelay user is used by other machines to send mail from Cron jobs und similar tasks through our mail server.
Is it possible to create a similar send-only user in Zimbra? In particular, I'd like for this user to not have a mailbox, so that no one can (accidentally or otherwise) send mail to this user. Also, I'd prefer if this could be done such that it doesn't use up a license.