I had a client who was alarmed by Microsoft reminding everyone that Office 2013 clients will no longer be supported by Office 365 and asked, “But I’m on Office 2013 and use Exchange Online… Is it going to stop working in two months?” And the answer is a resounding maybe. Which is not the current comforting reply, “no, everything is working fine”.
In an effort to continue developing their cloud service, Microsoft has affirmed that they will be dropping support for Office 2013 applications connecting to the Microsoft 365 service on October 13, 2020.
As has been done in the past, Microsoft will not “flip a switch” to administratively break connectivity for Office 2013 clients on October 13. Rather, this change in support means that all features released and changes made to the Microsoft 365 cloud services will not consider Office 2013 products in their support model and will not test these changes against Office 2013. Features added to the service on/after October 13, 2020 may not work for users connecting with Office 2013 clients and changes made after that date may partially or totally break Office 2013’s connectivity to Microsoft 365. As this is all ‘by design,’ Microsoft will not do anything about it. You will need to either upgrade your Office suite to a supported version or shift to using the browser-based Office Online apps.
This Microsoft Blog article from 2018 talks about the ongoing support model, including continued support for Microsoft 365 Apps for Enterprise (previously: Office 365 Pro Plus) and Office 2016/2019. The change in your Microsoft 365 admin panel is listed as MC175274.
Mainstream support for Office 2013 ended in April 10, 2015, but extended support is still valid until April 11, 2023. However, if you are a firm that uses Office 2013 in conjunction Microsoft 365 services, it is important to take action so that you are not affected by this change even if you have purchased extended support services from Microsoft. While we are not aware of any immediate changes that would cause you to lose connectivity to your data, such a change will likely happen suddenly and without warning.