How to stop being shut out of my account

Question

Since purchasing Microsoft 365 I have been repeatedly shut out of the account I have group emails in and told I have sent too many emails the second account from which I do not send group emails seems ok. I do not send more than 40 emails in a group and not more than fifty total in a day. Why is this happening

Answer 1

Hi Jenny,

A friendly reminder that this is a community support forum where users help other users. Advisors participating here cannot make changes to Microsoft services or access internal systems and can only provide technical guidance, independent of Microsoft's Policy decisions.

Microsoft's automated systems heavily throttle newly registered Microsoft 365 accounts until they establish a history of normal, human-like emailing patterns.

My recommendation would be to send Emails in 2 batches, with 20 recipients each.

Do not use a signature in the email as it directly tells Microsoft systems that it might be spam.

try switching the Email to Plain Text instead of HTML as a troubleshooting step to verify.

The setting is below:

1. Open the Gear icon > Settings.
2. Go to Mail > Compose and Reply.
3. Change the message format to Plain text.

I look forward to hearing from you to get the results of the troubleshooting.

Answer 2

Microsoft's automated anti-spam algorithms are flagging your group emails as automated spam, which triggers a protective lockout on your account.

While you are well under Microsoft 365's hard technical cap of 10,000 daily recipients and 500 recipients per single email, Exchange Online uses behavioral AI to monitor outbound mail. Your account is getting shut out due to the following specific rules:

Why Your Account Is Being Locked

• The Account Lacks "Credibility" (Warm-up Period): Microsoft heavily throttles newly registered 365 accounts. If a new email address immediately starts blasting the same message to 40 people simultaneously, the AI flags it as a "compromised or newly created spam bot" rather than an active human.
• CC/BCC Blasting vs. True Groups: If you are pasting 40 individual addresses into the "To", "CC", or "BCC" fields of a standard message, the server treats it as 40 individual delivery targets sent in an absolute millisecond. This sudden peak bursts past normal user-behavior thresholds.
• "Non-Relationship" Flags: If the 40 people in your group have never emailed you back, or if you are emailing them for the first time, Microsoft classifies them as "non-relationship recipients." This severely drops your internal sender reputation score.