How to fix Microsoft’s “service abuse mode” error

This post provides guidance for managing email systems without a dedicated email admin, focusing on resolving Microsoft 365's "service abuse mode" restriction, which occurs when an account is flagged due to spam complaints or suspicious behavior. The restriction is a provider-level block by Microsoft's anti-abuse systems, not an issue with Nylas integration. To resolve it, the account's Microsoft 365 admin must contact Microsoft Support to lift the block, allowing the user to re-authenticate and continue using the existing Nylas grant once the restriction is removed. Prevention strategies include ensuring recipients have opted in, avoiding cold emailing, maintaining consistent sending volumes, and promptly honoring unsubscribes. The post is part of a series offering practical advice for non-admins, with previous entries covering topics like email deliverability issues and reading Office 365 spam headers.