Hello,
OWA proxy happens when you have multiple sites and multiple CAS servers. For example:
1. A company has two sites in country A and B.
2. Country A has Exchange Server A with all roles installed. This CAS is internet facing.
3. Country B has Exchange Server B with all roles installed. This CAS is not internet facing.
4. OWA url is
https://contoso.com/owa point to the CAS server in Country A.
The OWA proxy will happens when the users on Country B access their OWA. CAS1 receives the OWA request from Internet and found the Users is on MBX B. Then it will proxy the request
to CAS B.
Thanks,
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