[quote]Hi. Is anyone clear on the relationship between the MX tab in
the Mail section of the panel, versus the MX tab in the DNS
Only use the second if the mail service is disabled entirely (under “Domains -> Manage”).
[quote]What I’d really like is for mail to normally go to another (non-DH) server,
but still use dreamhost as a backup.
Don’t do this. Our systems aren’t configured to serve as backup mail servers (at least not by default), so if you set our server(s) to be the backup MX, they will attempt local delivery, rather than holding onto it. In almost all cases, a backup MX introduces more potential problems than it solves - unless your primary MX is down a great deal, or will be down for more than 3-4 days at a time, deferred mail will generally be safely delivered once it’s back online.