Microsoft Unhappy with Customers Using Old Version of Exchange

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In a blog post, Microsoft noted that it now provides migration tools that allow you to move public folders from on-premises Exchange 2013 or earlier to Exchange Online. This was intentional, but Microsoft is now changing its stance on the matter.

Starting October 1, 2025, customers using Exchange 2010 or earlier versions of the software will no longer be able to use Microsoft tools to migrate their public folders to Exchange Online. Microsoft believes this removal will reduce reliance on legacy systems and improve 'long-term service reliability.'

Any attempt to migrate after that date will fail, so Microsoft has urged customers to complete the migration as soon as possible. If customers want to move their data to Exchange Online after October 1, they will first need to upgrade to a newer version of Exchange, which is Exchange 2013, but it's important to note that the supported versions are 2016 and 2019.

Microsoft has made it clear in a rather stern tone that it absolutely discourages the use of unsupported versions of Exchange Server. The company is making this announcement because it knows that public folder migrations from legacy systems are still ongoing, which is not recommended. Users should upgrade to Exchange Server 2016 or 2019 as soon as possible, but ideally Now consider moving to Exchange Server SE, as the other two versions are also reaching end of support.