Error sending message: Error sending message. MS365 returned status 403:

This issue may arise if you're attempting to send an email from an address different from the one connected with your Acctivate account. You can take these steps below to ensure that you're using the correct email address. 

Error sending message: Error sending message. MS365 returned status 403:
The user account which was used to submit this request does not have the right to send mail on behalf of the specified sending account., Cannot submit message. 

1. File > Configuration Manager > User > User Information > Click on the User that you want to configure.

2. There will be an email address box, please ensure that is the correct email that you're trying to use. 

3. On the bottom of the page, select the email provider that you're using such as SMTP, Gmail or Microsoft 365 and click "Connect" which will open a web browser page for you to sign into your email to connect with Acctivate. Once this is complete click save and you'll be able to email in Acctivate.