When setting up your own SMTP settings to use Office365 to send mail from SAP you must make changes to the authorizations of the sending account. If you need help with the SAP Settings see On Premise or Cloud Hosted guide.
After setting up the Mailer within SAP General Settings or the Mailer Service Settings in order to make this work you will need to follow the steps below to give it permission to Send As other users. For example, User1@example.com will need authorizations to send email as if it were from User2@example.com
1. Log into the Office365 Admin Center as your O365 admin, and click Exchange on the left side to get to the Exchange Admin Center
2. Next, click on Mailboxes on the left to display all of the mailbox names, then click on the mailbox that you want to add the “Send As” user(s) to. This would be the Username you have filled in the Administration > System Initialization > General Settings > Services: Company Specific Mailer
3. When you click on the account name, a box to administer that account will pop up on the right side of the screen, where you can click “Manage Mailbox Delegation” to add your “Send As” user
4. In the Manage Mailbox Delegation window, click the Edit button next to “Send As.”
5. Finally, click the Add Permissions button, then scroll down to the user you want to add as your “Send As,” and select them by checking the check box next to their name, you will need to do this for every user sending mail within SAP B1. Then click the Save button at the bottom of the window. You’re done!
All new users who join the organization and want to send email in SAP will require you to go through this process again to give your Send As user permissions for that user.