It can take up to six hours for new entries to be added to Microsoft's Address Book; the process that keeps everything in sync runs every six hours. In addition to affecting searches for contacts, this problem can prevent, temporarily, new additional accounts, such as EGAs, from being added to Outlook for Windows and Mac.

As a workaround for immediate needs, when searching for a contact, select All Users from the dropdown list.

To access accounts that can’t currently be added to Outlook apps, sign into Outlook on the web, click your profile in the upper right, then select Open another mailbox. Type the address of the account, then click Open.