Service messages from Microsoft
19 September 2023 at 21:32 BST
Title: We’ve detected an increase in email message rejections from multiple providers
User impact: If action isn’t taken, bulk messages sent with large BCC recipients may be rejected.
Current Status: We’ve detected an increase in rejections of bulk messages from multiple email providers. Please review the above recommendations and documentation to adhere to the bulk messaging best practices.
21 September 2023 at 22:18 BST
Title: Reminder to authenticate outbound email with SPF, DKIM, and DMARC User impact: If your organization hasn’t already taken action, bulk messages sent with large BCC recipients may be rejected.
Current status: Based on customer feedback, we’ve refined our messaging to better reflect that we’ve learned of multiple email providers (Gmail, Yahoo, and others) rejecting bulk email sent from Microsoft 365 for some organizations, though not necessarily from your organization. This is a reminder that to increase deliverability of legitimate email to external recipients, it is important to authenticate your outbound emails. Information on how you can get started with email authentication in Microsoft 365 can be found in the corresponding link listed in the Additional diagnostics section of this message. Additionally, the non-delivery reports (NDRs) from these providers include details and best practices on how to deliver email to them. Please remember that Microsoft 365 is not to be used for bulk email relay, but in case the receiving email providers perceive your email as such, please read the limitations and guidelines for outbound spam protection listed in the Additional diagnostics section of this message.