Office 365 Commercial customers can get the new Outlook for Mac by accessing their Office 365 Portal, (Gear icon Office 365 Settings Software Outlook for Mac icon) or visiting the Software page; Office 365 consumer subscribers can get the new Outlook for Mac by going to their My Account page. If you are not able to send/receive mail and 'Working Offline' appears at the bottom of your Outlook 2016/2013 page this is how you turn Outlook online. Click File Account Settings Account Settings. Select an Exchange or Microsoft 365 account, and then click Change. Under Offline Settings, move the slider to the desired amount of time, such as All, 12 months, 6 months, 3 months, or 1 month. Note: If you're using Outlook 2016, you can also select an amount of time as short as 3 days. How to Setup an Email Account in Outlook 2016 for Mac. Click the Work Offline button on the Send/Receive tab. The status will change to WORKING OFFLINE. Then click the Work Offline button again to turn it off and prompt Outlook to connect. Click File Options Advanced Send/Receive button and check When Outlook is offline uncheck. Outlook for Mac is in Offline Mode Resolution. If Outlook for Mac is offline then, you cannot send.
-->Symptoms
Outlook 2016 For Mac Update
In Microsoft Outlook 2016 for Mac, you are repeatedly prompted for authentication while you're connected to your Office 365 account.
Cause
Outlook For Mac 2016 Work Offline Version
This issue occurs because of the presence of duplicate tokens in the keychain.
Resolution
To resolve this issue in Outlook 2016 for Mac, install the February 2017 Outlook update (version 15.31.0) from the following Office website:
Workaround
To work around this issue, delete any cached passwords for your account, and also delete any modern authentication tokens from the keychain. To do this, follow these steps.
Note
Outlook 2016 Mac Work Offline
These steps affect all Office applications that use modern authentication.
Outlook For Mac 2016 Work Offline Greyed Out
Quit Outlook and all other Office applications.
Start Keychain Access by using one of the following methods:
- Select the Finder application, click Utilities on the Go menu, and then double-click Keychain Access.
- In Spotlight Search, type Keychain Access, and then double-click Keychain Access in the search results.
In the search field in Keychain Access, enter Exchange.
In the search results, select each item to view the Account that's listed at the top, and then press Delete. Repeat this step to delete all items for your Exchange account.
In the search field, enter adal.
Select all items whose type is MicrosoftOffice15_2_Data:ADAL:<GUID>, and then press Delete.
In the search field, enter office.
Select the items that are named Microsoft Office Identities Cache 2 and Microsoft Office Identities Settings 2, and then press Delete.
Quit Keychain Access.
Note
When you start Outlook, you are prompted to authenticate.