Microsoft recently issued a warning to Microsoft 365 email senders. They advised them to authenticate outbound messages. This action was 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.
By infosecbulletin
/ Sunday , June 15 2025
WestJet, Canada's second-largest airline, is looking into a cyberattack that has affected some internal systems during its response to the...
Read More
By infosecbulletin
/ Saturday , June 14 2025
Resecurity found 7.4 million records of Paraguayan citizens' personal information leaked on the dark web today. Last week, cybercriminals attempted...
Read More
By infosecbulletin
/ Friday , June 13 2025
HashiCorp has revealed a critical vulnerability in its Nomad tool that may let attackers gain higher privileges by misusing the...
Read More
By infosecbulletin
/ Friday , June 13 2025
SoftBank has disclosed that personal information of more than 137,000 mobile subscribers—covering names, addresses, and phone numbers—might have been leaked...
Read More
By infosecbulletin
/ Friday , June 13 2025
Serious security vulnerabilities in Trend Micro Apex One could allow attackers to inject malicious code and elevate their privileges within...
Read More
By infosecbulletin
/ Thursday , June 12 2025
Aim Labs discovered a zero-click AI vulnerability named “EchoLeak” in Microsoft 365 Copilot and reported several ways to exploit it...
Read More
By infosecbulletin
/ Wednesday , June 11 2025
On Tuesday, Adobe released security updates for 254 vulnerabilities in its software, mainly affecting Experience Manager (AEM). There are 254...
Read More
By infosecbulletin
/ Wednesday , June 11 2025
A new report from Bitsight reveals that over 40,000 internet-connected security cameras around the world are exposed, broadcasting live footage...
Read More
By infosecbulletin
/ Wednesday , June 11 2025
Microsoft's June Patch Tuesday update has arrived, addressing 66 vulnerabilities across its product line. One of these flaws was actively...
Read More
By infosecbulletin
/ Tuesday , June 10 2025
More than 84,000 Roundcube webmail installations are at risk due to CVE-2025-49113, a severe remote code execution (RCE) vulnerability that...
Read More
ALSO READ:
EC summoned Lands Ministry’s IT team and vendor intelligence clearence report
“This is especially important when sending bulk email (large volume email), as it helps maintain the deliverability and reputation of your email campaigns.”
Not following new email authentication standards can cause emails to be rejected or marked as spam.
Microsoft has cautioned against using Microsoft 365 for sending large amounts of emails. If emails exceed the sending limits, they may be blocked or sent to special delivery pools identified as high risk by the outbound spam controls in Exchange Online Protection (EOP).
Organizations that want to deliver bulk emails through EOP will have to abide by this outbound spam protection guidance:
- Exercise caution not to exceed the sending limits in the service by sending emails at a high rate or volume. This includes refraining from sending emails to a large list of BCC recipients.
- Refrain from using addresses in your primary email domain as senders for bulk emails, as it may impact the delivery of regular emails from senders within the domain. Instead, consider utilizing a custom subdomain exclusively for bulk email.
- Ensure that any custom subdomains are configured with email authentication records in DNS, including SPF, DKIM, and DMARC.
Microsoft warns that following their recommendations does not guarantee delivery. If your email is rejected as bulk, they suggest sending it through on-premises or a third-party provider.