Unable to send email

Sree 1,966 Reputation points
2021-09-02T17:22:53.537+00:00

Unable to send email via smtp.office365.com

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
2,897 questions
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.
6,091 questions
1 vote

Accepted answer
  1. Tasadduq Burney 7,186 Reputation points Microsoft MVP
    2021-09-03T07:38:29.77+00:00

    Hi,

    You could take these into consideration:

    1. Please check and turn off the firewall or any other scanning software temporarily.
    2. Make sure the sending server's IP is not on an SMTP block list.
    3. Verify that the receiving server is configured to use TLS.
    4. Check if the receiving server is configured to only respond to SMTP (not ESMTP) commands. TLS is part of the ESMTP protocol.

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