Where is my Shared Mailbox in Outlook Web?
How do I open a shared mailbox in Outlook Web (outlook.office.com)?
In Outlook desktop on Windows, a shared mailbox is normally 'automapped', so no action is required.
In https://outlook.office.com (Outlook Web, OWA), it has to be manually opened once - then it remains open in the folder list.
1. In the list of folders, right click the word 'Folders'
2. On the menu, click 'Add shared folder or mailbox'
3. Type the first three characters of the mailbox name, then pick it from the suggestions by clicking it
4. Click Add
The shared mailbox will now be found towards the bottom of your folder list
Get in touch with The Microsoft 365 Chap if you need help with Outlook.