coreFORCE - Website - Troubleshooting Email sent through Office 365

Use an app password instead of a user password for all email accounts.  App passwords are generally more secure than user passwords and are not subject to password expiration policies.  However, not all Microsoft 365 accounts are permitted to use App passwords.

Microsoft Multifactor Authentication End User App Passwords

If you have access to the administrator settings for your Microsoft 365 domain, this article may be helpful in turning on app passwords:

How To Enforce Multifactor (MFA) App Passwords

Some licenses for Microsoft 365 do not include App passwords, so for those accounts it is not possible to turn them on.  In that case, you would need to use a user password.  However, sending email via SMTP may not be enabled for a user account.  You will need to enable Client SMTP on the individual mailbox. It defaults to unchecked. 

This Microsoft article explains that and has a few more things to try:

Fix issues with printers, scanners, and LOB apps that send email using Microsoft 365

Note that although this article refers to sending email from a printer, the underlying system is the same; coreFORCE can be considered a Line-of-business (LOB) application.

Updated on: 11/20/2025