Sending email via Office 365 using PowerShell

January 22, 2020
Update 11/12/23 — Microsoft GraphAPI is now the preferred method for sending email using O365. Refer to this blog entry

This post is really more about the potential problems one might encounter using Send-MailMessage cmdlet in PowerShell to connect and send email via Office 365.

First a quick example:

[SecureString]$o365Password = ConvertTo-SecureString "Your Office 365 Account Password" -AsPlainText -Force
[PSCredential]$o365Credentials = New-Object System.Management.Automation.PSCredential("Your Office 365 Account Username",$o365Password)
Send-MailMessage `
  -Subject "Your Subject" `
  -Body "Your email message" `
  -To "" `
  -From "" `
  -SmtpServer "" `
  -Port 587 `
  -Credential $o365Credentials `

If the above settings are set correctly the email should be sent.

Some errors you may encounter:

Send-MailMessage : The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.57 SMTP; Client was not authenticated to send 
anonymous mail during MAIL FROM []
  • Possibly expired or deactivated Office 365 account
  • Confirm username and password by logging into Outlook web access
  • Confirm connecting on port 587
  • Confirm -UseSSL parameter provided
Send-MailMessage : Unable to connect to the remote server
  • SmtpServer parameter is set to “”. Lots of other solutions suggest alternatives that may have worked in the past, but did not work for me.


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about me

An information technology professional with twenty five years experience in systems administration, computer programming, requirements gathering, customer service, and technical support.