Microsoft to Fight Spam with Exchange Online Bulk Email Limits
Microsoft will introduce new measures to combat spam mail through Exchange Online Bulk Mail limits, which will come into effect starting next year. The new limits will be applied in two stages.
Fighting Spam Emails Microsoft is preparing to impose a daily limit on bulk emails sent via Exchange Online for 2,000 external recipients.
The measure is expected to come into effect from January 2025. Exchange Online does not support sending bulk or mass emails from a single account.
Microsoft's new External Recipient Rate (ERR) limits aim to prevent customers from misusing Exchange Online resources and to restrict usage.
Exchange Online currently applies a recipient rate limit of 10,000 recipients. The Exchange team stated, "The 2,000 ERR limit will become a sub-limit within this 10,000 recipient limit." However, these changes will not alter the recipient rate limit. The team explained, "If you send emails to fewer than 2,000 external recipients within 24 hours, you can still send emails to a total of 10,000 recipients."
The new limit will be introduced in two phases: initially, starting from January 1, 2025, it will apply to all new users with cloud-hosted mailboxes; in the second phase between July and December 2025, Microsoft will begin applying the limit to existing users with cloud-hosted mailboxes.
To do this, Exchange Online customers with cloud-hosted mailboxes that exceed the ERR limit must switch to Azure Email Communication Services, a service specifically designed for business-to-consumer communication via high-volume email.
Despite these changes, Google has been applying stricter spam limits and authentication guidelines for bulk email senders since April 1st as a way to protect against attacks.
Users who wish to send more than 5,000 messages per day to Gmail accounts should configure SPF/DKIM and DMARC email authentication for their domains.
Source: Microsoft Will Combat Spam with Exchange Online Bulk Email Limitations (itsecurity.pt)