Usage of EV Office Mail App in a second mailbox (Open another mailbox) in OWA

[Marcde]

Hello together,

consider the following situation:

-User A is having access to the office mail app in OWA and its loading correctly. Same for user B when he is logging into OWA.

-User A logs into OWA and opens the mailbox of user B (Open another mailbox). The office mail app does not even appear.

Is this by design or can this be changed?

[VirgilDobos]

Hello,

Can you give user A full permissions on both Mailbox B and Archive B then retry?

[Marcde]

Already did that.

The Enterprise Vault button to load the office mail app is not even showing.