Hi @Vinay Bhatia ,
Is the shared mailbox is added as a seperate email account in the same profile with the user's primary account, that is, both accounts are listed under the Email tab when you check it via File > Account Settings > Account Settings? If this is the case, it's an expected behavior that the reminders for the shared mailbox will also pop up.
Assuming the user has full access to the shared mailbox, agree with Andy you can let the shared mailbox auto-mapped to the user to avoid calendar reminders for the shared mailbox.
An alternative is to add the shared mailbox as an additional maibox:
- Go to File > Account Settings > Account Settings > Email.
- Double click on the user's account, choose More Settings > Advanced > Add, type the shared email address, such as shared@Company portal .com:
- Choose OK > OK, choose Next > Finish > Close.
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