The remote SMTP service does not support TLS

Hanh Trinh 41 Reputation points
2021-07-27T01:29:38.177+00:00

Hello everyone,

Yesterday we got the issue with the SMTP server :

" Message delivery to the host '40.100.2.98' failed while delivering to the remote domain 'my domain' for the following reason: The remote SMTP service does not support TLS.

The SMTP verb which caused the error is 'STARTTLS'. The response from the remote server is '250-HK2PR02CA0207.outlook.office365.com Hello [my ip]

250-SIZE 157286400

250-PIPELINING"

We have configured SMTP server for printer machine forwarded document when scan to email.

Nothing changed in our system, but the printer machine can't be sent an email to delivery when scanning a document.

The printer server printed error page : Start TLS unsupported .

Do you know about the solution on my issue ?

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  1. Joyce Shen - MSFT 16,641 Reputation points
    2021-07-27T08:39:01.597+00:00

    Hi @Hanh Trinh

    Could you please tell more information about your environment? Are you failed sending messages to O365 using the printer which configured to send mails with your SMTP server? Please correct me if I have any misunderstanding about your question.

    In addition what mail server are you using now?

    Below is a related thread discussed about the similar issue for your reference: SMTP relay Windows server 2012 rejected auth negotiation
    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    The error occurs when you are forcing the use of encryption for email transport, and the receiving server does not support this. TO send to these you have to use no TLS, via changing to opportunistic TLS, assuming you have no legal requirement to force transport encryption. Going to opportunisitc TLS will encrypt traffic when it can and for those that can't accept encrypted traffic will send the email unencrypted.

    In addition, we could also refer to the official document which introduces about Sending mail directly from your printer or application to Microsoft 365 or Office 365 (direct send) , check if the method introduced here suitable for your scenario.

    If an Answer is helpful, please click "Accept Answer" and upvote it.

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