Dynamics 365 Business Central SMTP Mail Setup Error
Update on March 16, 2022 - this functionality will no longer be available in Business Central with the version 20 update Wave 1 in 2022. You will need to use the new email functionality. Learn more here.
Originally posted on March 11, 2020
I recently made a copy of my company within Business Central and in the new copied company ran into issues being able to email out. Within the SMTP Mail Setup window when I tried to Test Email Setup and received the following error message: The mail system returned the following error: "A call to MailKit.Net.Smtp.SmtpClient.Authenticate failed with this message: 5.7.8 Username and Password not accepted. Learn more at 5.7.8 https://support.google.com/mail/?p=BadCredentialsr20sm7383407qtt.6 - gsmtp".
While troubleshooting the issue I determined that I was able to successfully test in the main company but not the copied company. I removed the Password from the SMTP Mail Setup window within the copied company and re-entered it and was able to then test with success.