The response from the remote server was

IT Operation Manager 1 Reputation point
2022-09-03T04:42:29.733+00:00

Dear Reader,

I'm facing issue sometime with SMTP of office 365. it's giving The response from the remote server was: 334. It's been around 1 month, we are facing this issue.

Please advise the permanent fix for this.

Regards
Dinesh Kumar

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.
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  1. Vasil Michev 97,306 Reputation points MVP
    2022-09-03T07:01:04.99+00:00

    Make sure you are using TLS1.2, and if that's not an option use the legacy endpoint: https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/opt-in-exchange-online-endpoint-for-legacy-tls-using-smtp-auth
    Also make sure the account you're authenticating with is properly licensed and enabled for SMTP auth: https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission

    1 person found this answer helpful.