It is incorrect. The redirect/mirror/parked/cloaked options of the DreamHost Panel under “Manage Domains” apply to Web hosting only.
One can mirror email addresses using the “Custom MX” panel in the Mail section.
Interestingly, it appears one can no longer enable or disable mail service on a per-domain basis anymore.
I’ve updated the Redirect Domain and Mirror Domain Wiki articles to reflect the DreamHost Panel options.
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