MS Outlook and MS ActiveSync Protocol Deprecated

It seems that Microsoft is deprecating the MS ActiveSync protocol on Microsoft Outlook. If you are having a tough time connecting, or have trouble synchronizing mail, and are using the ActiveSync protocol you may have installed a newer version of Microsoft Outlook (greater than 16.0.17126.20132). Here are some options to resolve the situation.

We have three solutions. The first is to downgrade Microsoft Outlook using the following procedure. This version continues to work (16.0.17126.20132). The second option is to stop using Microsoft Activesync and use IMAP instead. You will not have the same level of synchronization with contacts and calendars though. The third and final solution would be to switch over to the EM client (https://www.emclient.com/). This is a replacement to Microsoft Outlook. It is a paid product but you can get a free license in your account at EPhost. You will need to pay for additional licenses beyond those.

Try the 3M Client

1. Download and install the EM Client software.
2. Install eM Client license. 
   1. Login as a Domain Administrator (click the green Control panel button)
   2. Go to Domain Settings
   3. Select eM Client from the tree menu.
   4. In the content pane, click the Request Code button on the Verify Domain card.
3. Configure your email account using MS ActiveSync. *

* https://www.ephost.com/account/index.php/knowledgebase/440/Email-Settings-POP3-or-IMAP-or-Microsoft-365.html#activesync  

Downgrade MS Outlook. 

Please confirm you are on a version greater than 16.0.17126.20132, and then Follow the instructions below.

1) Please see the workaround solution here: https://www.reddit.com/r/sysadmin/comments/1ajnfqq/latest_outlook_365_2401_causes_activesync_to_no/

Instructions:

A. Steps to Downgrade

1. Open CMD as admin
2. Paste this command:
   "C:\Program Files\Common Files\microsoft shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.17126.20132
3. Press enter and wait till the downgrade is done.

B. It's probably also best to disable updates in Outlook until the release a patch:

1. Launch application and click the File button top left.
2. Select the Office Account option located bottom left.
3. Click the Update options button and select the Disable Updates option from the dropdown menu.

Convert to IMAP Protocol

1. Configure your email account using IMAP instead. *

* https://www.ephost.com/account/index.php/knowledgebase/440/Email-Settings-POP3-or-IMAP-or-Microsoft-365.html#activesync