We have a user who has access to their own in box and they receive email alerts for this no problems.
However they also have access to another shared mailbox which is auto mapped (he is not getting notifications for this but wants them).
My colleague has said the solution to enable notifications on this second mailbox this is to manually add the mailbox (is this correct? it doesn't seem to make any sense, why would manually adding a mailbox be better than an auto mapped mailbox?).
He also said if we manually add a mailbox which is already auto mapped Outlook/Exchange should figure this out and remove one of the duplicate mailboxes?
Automapping limits many of the built-in functionalities in Outlook, including rules, OOO, archive access and so on. If you want the full experience, add the shared mailbox as additional account instead (File > Add account). And no, Outlook will not "figure this out", you have to remove the automapping bit to prevent potential issues.