Fix: Outlook 2016/2013 Always Starts in Offline Mode

Users of one in every of my buyer have reported that Outlook at all times begins in the offline mode. Obviously, e-mails can’t be despatched or obtained, and the Outlook icon in the system tray has a crimson cross on it with the next message: “Microsoft Outlook is offline”.

Outlook 2016 / 2013 always starts in offline mode

To disable Outlook offline mode, every time a consumer has to press the corresponding button (“Work Offline“) on the Send/Receive tab. But the following time you begin Outlook, it begins offline once more. You need to disable offline mode once more in the Outlook settings. It is obvious that the fixed want to change Outlook from Offline to Online is extremely annoying to customers.

outlook 2016 work online button

If there is no such thing as a “Work Offline” button, it implies that the Cache Exchange Mode is disabled in your Outlook.

Only some customers with Outlook 2016 or 2013 face this downside. User mailboxes are situated on an Exchange server and there are not any connectivity issues and no errors in the Exchange logs.

Outlook can robotically go offline in case of any community/Exchange connection issues (after 10 failed makes an attempt to connect with the mailbox server). So initially, we checked the community operation (switches, routers, firewall guidelines) – every part labored usually.

Here is what else we checked when diagnosing the issue:

  • The accessibility of a mailbox by means of the OWA interface: the mailbox was out there;
  • In Exchange 2010, that you must verify the CAS server availability from the consumer pc thought port TCP/135 (RPC locator). You can do it utilizing the cmdlet: tnc ber-msgcas –port 135the port is on the market. In Exchange 2013/2016, the primary protocol for connecting Outlook shoppers to CAS is HTTPS (), so it suffices to verify the provision of port TCP/443;
  • We began Outlook in the Safe Mode (outlook.exe /protected command) and disabled all Outlook add-ons: the issue endured;
  • We tried to delete an Outlook profile and re-create it once more. We reinstalled and repaired Outlook – nothing helped.

The resolution was surprising: all customers who reported Outlook begin offline downside had Skype for Business (Lync) put in. As it turned out, if Lync and Outlook are began on the similar time, altering Offline mode will not be saved after Outlook is closed (Lync someway blocks saving offline mode settings, perhaps, because of its fixed connection to Exchange).

Thus, to disable working Outlook in the offline mode, you simply need to shut Lync / Skype4B (guarantee that there are not any processes in the Task Manager) and disable Work Offline mode in Outlook.

After that you could run your Lync (Skype4B). The subsequent time Outlook begins on-line.

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