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Dynamics 365 Community / Forums / Small and medium business | Business Central, N... / Sudden SMTP Error when...
Small and medium business | Business Central, N...
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Sudden SMTP Error when sending mail in BC.

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Posted on by TimHodge 16
Our SMTP Mail in BC has been working without problem until exactly 13:45 (UK Time) yesterday (6th August 2024) when it started to throw this error:
 
The SMTP server rejected the authentication request, as the authentication data is incorrect. Verify that your Username and Password are correct and that the SMTP server supports the specified authentication type (Basic). SMTP error code: 535.
 
We are using SMTP Basic Authentication with an Application Password for MFA purposes, I have even created another Application Password in case the original had expired for some reason, although there is nothing to suggest that.
 
Any ideas as to why this would suddenly happen, I know SMTP Basic Authentication is due to be removed at some point but, BC still doesn’t seem to support OAuth 2.0 and mail is a vital function so we need a solution ?
Categories:
Dynamics 365 Business Central
I have the same question (4)
  • Suggested answer
    Khushbu Rajvi. Profile Picture
    Khushbu Rajvi. 20,275 Super User 2025 Season 2 on at
  • MarceloBorges Profile Picture
    MarceloBorges 122 on at
    Who's your SMTP Mail provider?
  • TimHodge Profile Picture
    TimHodge 16 on at
    Just using smtp.office365.com always have done and it’s been fine until yesterday.
  • MarceloBorges Profile Picture
    MarceloBorges 122 on at
    I ask because SMTP errors usually happen on the SMTP Server side, not in BC. If you had told me you were using, for example, a GMail SMTP server, I would have you search with Google for issues with authentication.
     
    But you mentioned you are using Microsoft's own SMTP Server...  then it raises another question: What NAV/BC version are you using? Couldn't you use the out-of-box email connector to connect to your MS email account?
  • TimHodge Profile Picture
    TimHodge 16 on at
    Latest version of online Business Central, not sure what you mean by ‘out of the box’ connector this is standard email configured in BC ?
  • TimHodge Profile Picture
    TimHodge 16 on at
    Sorry, I do know what you mean but, we can’t use the Microsoft 365 Connector because our Mail and BC are in different tenancies. Painful historical reasons why and I wish it wasn’t the case but, sadly it is and that means SMTP is the only option.
  • MarceloBorges Profile Picture
    MarceloBorges 122 on at
    Understood. Do you have any other way of testing if your SMTP credentials work in any other software rather than BC?
  • TimHodge Profile Picture
    TimHodge 16 on at
    It is a generic SMTP issue with Microsoft having deprecated Basic Auth, our Dynamics Partner are talking to Microsoft about getting SMTP working with OAuth 2.0 in BC but, even they don’t seem to know how to configure that successfully. We have had no mail in BC for two weeks now, it really isn’t good enough.
  • TimHodge Profile Picture
    TimHodge 16 on at
    Have had no option other than to subscribe to a third-party mail solution to resolve this problem.
     
    Turning off Basic Authentication for SMTP has not been a good move by Microsoft.
  • Suggested answer
    Amit Profile Picture
    Amit 2,557 on at
    Hi,
     
    Please check your email authentication in the email setting. Please coordinate with administrator for checking the settings.
     
     
    Regards
    Amit Sharma

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