some users have the need to send newsletter regularly to external / internal users, and when sending to internal users (student/teachers), it oftens takes long time and cause other regular emails delayed for 30 or 40 minutes.
thus, is it possible to set these user's zimbraMailHost attribute to other smtp server, so that all emails for these users are routed to that smtp server and reduce zimbra mail server's load?
actually, i've tried to set this attribute by "zmprov ma" command and ldapmodify, but failed to do so.
ERROR: service.INVALID_REQUEST (invalid request: specified zimbraMailHost does not correspond to a valid server service hostname: (new.smtp.server)
any other advice? Thanks.