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Microsoft 365 Deprecated Connectivity

Prepare for “The RPCalypse”

In October 2017, the Office 365 email platform will deprecate the use of RPC over HTTP, the protocol used by Outlook clients to connect to mailboxes. The new protocol will be MAPI over HTTP (MAPI/HTTP).

The actions to take before then are:

  • Remove Outlook 2007 and replace with a later version;

  • Ensure Outlook 2013 is fully updated.

No further action should be required as compatible Outlook clients will reconfigure themselves according to the Autodiscover protocol.

Office 365 SSL/TLS Support

In October 2020 (previously March 2018, then June 2020), Microsoft 365 will only support TLS 1.2. This means that some down-level clients will fail to connect, either via browser, Exchange Active Sync or MAPI over HTTP. These clients include:

  • Windows XP/2003/Vista;

  • Internet Explorer 10 or lower on Windows 7;

  • Android 4.3 and lower;

  • iOS 4.0 and lower.

Legacy Authentication Retirement

In October 2020 the first half of 2021, legacy authentication protocols for Exchange ActiveSync, POP and IMAP usage will be retired. This means that older email clients which do not support Modern Authentication or OAuth 2.0 will be unable to connect.

Devices such as multifunction printers and other apps which use authenticated SMTP to transmit messages via Microsoft 365 will not be affected.

Older Clients Unsupported

From October 21, 2020, Microsoft Outlook 2010 and 2013 will not be “supported” connecting to Microsoft 365 cloud services. This doesn't mean it won't work, only that Microsoft does not guarentee they will work.

Office 2016 and Office 2019 will be supported to October 2023.

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