How to read Office 365 spam headers: A simple guide for non-admins

In the absence of an email administrator, individuals such as developers, support leads, or office managers may find themselves responsible for diagnosing why emails are marked as spam in Office365. Microsoft provides reasons for spam designation through complex, acronym-heavy spam headers, particularly the X-Forefront-Antispam-Report. This guide offers a practical breakdown of these headers, advising users to examine key elements such as the sending IP evaluation (IPV), the Spam Confidence Level (SCL), and the Summary of Filter Verdicts (SFV) to understand Microsoft's spam filtering decisions. By checking the sending IP's reputation, adjusting message content, and understanding filter verdicts, users can address issues without needing deep expertise in Exchange or security. The guide is part of a series aimed at assisting those who find themselves unexpectedly managing email systems.