Microsoft working on fix for ongoing Outlook email issues
​Microsoft is working to resolve an Exchange Online issue causing email access problems for Outlook mobile users who use Hybrid Modern Authentication (HMA). HMA is a Microsoft Exchange Server feature that allows users to access on-premises mailboxes using authorization tokens from the cloud. Tracked under EX1137017 in the Microsoft 365 Admin Center, this known issue is caused by a recent service change, designed to improve the efficiency of mailbox syncs, which is triggering 12-hour sync delay