We have 2 sites, Prod and DR. We're doing a DR test externally from an ISP perspective, no Exchange DB or server failovers. All mailboxes are in Prod (site1). External access goes to mail1.domain.com which goes to prod. We will be repointing that DNS to the DR site, which points to the DR exchange server. Prod and DR Exchange servers (site1 and site2) are in the same DAG.
When outlook anywhere connects to the DR Exchange server, it will say your mailbox is on Exchange server in the other site, what will happen? Does it use the External URL? Will it loop?