Security News > 2023 > October > Microsoft 365 admins warned of new Google anti-spam rules

Microsoft 365 email senders were warned by Microsoft this week to authenticate outbound messages, a move prompted by Google's recent announcement of stricter anti-spam rules for bulk senders.
"By setting up email authentication for your domain, you can ensure that your messages are less likely to be rejected or marked as spam by email providers like Gmail, Yahoo, AOL, Outlook.com," the Microsoft Defender for Office 365 team said.
Failure to follow newly announced email authentication standards might lead to emails being rejected or tagged as spam.
Microsoft also warned that the Microsoft 365 service should not be used for bulk emailing, as emails not following sending limits will be blocked or sent to special high-risk delivery pools by outbound spam controls built within Exchange Online Protection.
As part of these efforts to combat spam, Google said it will also closely monitor spam thresholds and, in cases where abusive bulk senders are identified, it will mark their emails as spam to protect users from unsolicited and potentially harmful messages.
"If you don't meet the requirements [.], your email might not be delivered as expected, or might be marked as spam," Google warned.
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