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unable to send email

Glenn Maxwell 13,511 Reputation points
2023-08-25T18:02:58.9466667+00:00

Hi All

I am trying to trigger a test email using the below syntax i am getting error. if i am using onprem relay i am not seeing any issue if i use office365 relay i am facing issue. exchange online plan1 license is assigned to the service account. sender and recipient email is my domain.

Send-MailMessage -SmtpServer smtp.office365.com -Credential $credential -From '@contoso.com' -To '@contoso.com' -Subject 'Test' -Port 587 -UseSsl STARTTLS

Send-MailMessage : The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 Client not authenticated to send mail.

Error: 535 5.7.139 Authentication unsuccessful, the user credentials were incorrect.

Exchange Online
Exchange Online

A cloud-based service included in Microsoft 365, delivering scalable messaging and collaboration features with simplified management and automatic updates.

Exchange | Exchange Server | Other
Exchange | Exchange Server | Other

A robust email, calendaring, and collaboration platform developed by Microsoft, designed for enterprise-level communication and data management.Miscellaneous topics that do not fit into specific categories.

Exchange | Exchange Server | Management
Exchange | Exchange Server | Management

The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization.

Exchange | Hybrid management
Exchange | Hybrid management

The administration of a hybrid deployment that connects on-premises Exchange Server with Exchange Online, enabling seamless integration and centralized control.

Answer accepted by question author
  1. Aholic Liang-MSFT 13,921 Reputation points Microsoft External Staff
    2023-08-28T09:41:37.2533333+00:00

    Hi Glenn Maxwell,

    Please use the following command:

    Send-MailMessage -SmtpServer smtp.office365.com -Credential $credential -From '******@contoso.com' -To '******@contoso.com' -Subject 'Test' -Port 587 -UseSsl

     

    Note: that the -UseTSSL switch should not use any parameters, such as STARTTLS.

     

    In addition, check the following settings for SMTP AUTH:

    1. Disabling security defaults
    2. Check if SMTP authentication is enabled for this user
    3. Exclude the user from a Conditional Access policy that blocks Legacy Authentication
    4. Disable Multi-Factor Authentication (MFA) on the licensed mailbox that's being used

    Please refer to this link for details： Fix issues with printers, scanners, and LOB apps that send email using Microsoft 365 - Exchange | Microsoft Learn

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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  1. Rajesh Kumar (IT)/GG 0 Reputation points
    2024-10-23T09:29:34.89+00:00

    Send-Mailmessage : Mailbox unavailable. The server response was: 5.7.1 Unable to relay for"Email-ID"

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  2. Glenn Maxwell 13,511 Reputation points
    2023-08-25T18:35:46.56+00:00

    I am getting the below error when i remove ssl

    Send-MailMessage -SmtpServer smtp.office365.com -Credential $credential -From  '******@contoso.com' -To ' ******@contoso.com ' -Subject 'Test' -Port 587 STARTTLS

    The server response was: 5.7.3 STARTTLS is required to send mail

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