There two options: add domains and addresses to the safe or blocked lists in Exchange admin center or to Outlook using powershell.
Outlook 2016 users are discovering that after updating to builds 7870.2020 and higher, search stops working for POP accounts and PST files.
A shared mailbox can be a practical solution for any business with groups of people working from different locations.
With the right permissions, any person in a group can access a shared mailbox that appears in their address book.
Users with POP3 or IMAP accounts who created accounts using their own email address, to sync just their calendar and contacts have noticed a problem after their account was migrated to the new server and opened in Outlook 2016: all replies use the account, not the account that downloaded the message.
An administrator wanted to know if he could set up global safe and blocked lists for distribution to his users.
One caution: If the calendar folder is using a custom Outlook form, access the folder only through the folder list.
The latest Outlook security update is causing problems with i Cloud (and attachments).
A registry key is now available that will allow i Cloud (and other affected MAPI services) to work with the patch installed.
If you access it through the Favorites hierarchy or the Other Calendars list, Outlook 2003 is likely to experience corruption of the custom forms cache. I've checked your problem and it works with my Outlook 2007 as described by Sue the following way: The trick to adding a public folder calendar to the Other Calendars list is to switch to the folder list and drag the calendar folder to your Public Folder\Favorites area.
Microsoft has a hotfix designed to solve this problem.