The response from the remote server was

Question

The response from the remote server was

IT Operation Manager 1

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

KyleXu-MSFT 26,396 Reputation points

2022-09-05T09:27:34.87+00:00

@IT Operation Manager

Do you mean that you get the 334 error when send as email from Gmail to Exchange online mailbox?

If not, could you tell us how this issue occur?

1 answer

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KyleXu-MSFT 26,396 Reputation points

2022-09-05T09:27:34.87+00:00

@IT Operation Manager

Do you mean that you get the 334 error when send as email from Gmail to Exchange online mailbox?

If not, could you tell us how this issue occur?

Answer 1

Vasil Michev 119.6K MVP Volunteer Moderator

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

IT Operation Manager 1 Reputation point

2022-09-03T07:13:17.27+00:00

Dear Michev,

Thanks for the suggestion.

I have ensured these settings. SMTP is enabled for the user and legacy smtp is also enabled.

I'm using Send As feature of Gmail and sending emails from Gmail. The issue is not permanent, if we send 5-6 emails then error may occurred for 1-2 emails only.

And It's been 1 month, we are facing this issue.

Regards
Dinesh Kumar

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The response from the remote server was

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