If you're referring to the Test Email in the Workflow Setup window of Dynamics GP, the test email simply uses the SMTP server name and account information you've entered into the Workflow Setup window, and then sends it to the email address you specify when sending the test email.
If the Test Emails are not working, the majority of the time there is an issue with the SMTP information entered in that window.
If you're using an O365 SMTP server or account information in the Workflow Setup window, and the test email is failing, try creating a new, non-O365 email account such as outlook.com and use that information in the Workflow Setup window, which will help verify whether the issue is with the O365 SMTP information or not.
1. Use an Outlook.com email account for the SMTP information.
a. Create an Outlook email account at Outlook.com by signing up and creating an email account for @outlook.com.
b. Use the SMTP information for this new Outlook.com email account in the Workflow Setup window for the SMTP information, such as this example:
-- E-Mail Address: User@outlook.com
-- Display Name: User Name
-- smtp-mail.outlook.com
-- Port: 587
-- Mark the option of 'This server requires a secure connection (SSL).'
c. Under the 'SMTP Authentication' section of the Workflow Setup window, mark 'Basic Authentication' and then enter the required information such as this example:
-- User Name: user@outlook.com
-- Password: (enter password for this outlook.com email account)
-- Confirm Password: (re-enter password for this outlook.com email account)
d. Click Ok to save changes and then re-open the Workflow Setup window and click the 'Test E-Mail' button to attempt to send a test email to yourself at your email address, to confirm whether you receive it or not.
We've also seen with O365 email accounts and email functionality in Dynamics GP, where not having legacy/basic authentication enabled along with the 'modern' authentication on the O365 account, can cause emails not to work in Dynamics GP.
Also, having multi-factor authentication (MFA) setup on an O365 account can sometimes cause issues with email functionality in Dynamics GP.
Let us know if you have any questions.
Thank you
