Outbound Blocked Email - SPAM

Darek L 21 Reputation points


I have got a problem with sending invoices via ERP system from 3 august 2021. When invoices are sending "Office 365 Defener" is blocking account using to send mails with invoices. I can unlock this account in "restricted users", but situation repeats about 3 days.
I tried add rule in threat policy. The result was account was not seen in "restricted users" but it was blocked either. I have no idea where I can aprove this account for sending mails via ERP system.

I will be grateful for your help.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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Accepted answer
  1. Yuki Sun-MSFT 40,906 Reputation points

    Hi @Darek L

    Agree with michev that sending bulk email via Office 365 is actually not a supported use of the service.

    According to the Exchange Online limits, "To discourage the delivery of unsolicited bulk messages, Exchange Online has recipient limits that prevent users and applications from sending large volumes of email. These limits are applied per-user to all outbound and internal messages." And as mentioned in the Note, it's recommended to use third-party providers that specialize in these services for your requirement to send bulk messages:

    The following official document also mentioned that the recommended solutions are sending bulk messages through on-premises email servers or a third-party bulk email provider:
    Recommendations for customers who want to send mass mailings through EOP

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  1. Vasil Michev 98,206 Reputation points MVP

    Sending bulk messages via O365 is not a good idea, best use a service that specializes in this. Otherwise you risk blocking your users and even domain.

    1 person found this answer helpful.
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