Agents are 8.0.2HP2 on Windows servers
Client is 8.0.2HP3

Two users.

First Test
User 2 is not listed as a Proxy into User 1's account at all.
User 2 cannot add User 1's calendar to Multi-User view. User 2 gets a D124 - Access to [user1@etmc.org] is denied.

Second Test
User 2 is listed as a Proxy into User 1's account but has no Read/Write permissions to anything.
User 2 cannot add User 1's calendar to Multi-User view. User 2 gets a D124 - Access to [user1@etmc.org] is denied.

Third Test
User 1 gives User 2 Read/Write proxy access to Mail only.
User 2 can add User 1's calendar to Multi-User view. It's blank, of course, even though appointments, tasks, and reminder notes do exist on that day's calendar for User 1.

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So, why can User 2 add User 1's calendar to the Multi-User view even though User 2 has not been given any proxy access into User 1's calendar?

Not that it matters to anybody yet, it's just odd behavior.