Email setup in Dynamics 365 Business Central has changed since the standalone SMTP Email Setup page. Modern Business Central uses the Email Accounts framework, but the issue that most often trips people up, a send-on-behalf error on the test message, still has the same root cause. This guide covers both.
How email setup works today
Business Central now configures email through Email Accounts rather than a single SMTP page:
- Choose the search icon, enter Set Up Email, and run the assisted setup, or open the Email Accounts page directly.
- Add an account and choose a connector. The Microsoft 365 connector is the recommended option for organisations already on Microsoft 365; SMTP and Current User connectors remain available for specific cases.
- Fill in the fields. Hover over a field to read a short description.
- Use Send Test Email to confirm the account works, then set a default account if you run more than one.
The legacy SMTP Email Setup page and its standalone configuration were deprecated by Microsoft in favour of this account-based model, so new setups should use Email Accounts rather than the old SMTP page.
The common error: not allowed to send on behalf of the user
A frequent problem is that the test email connects to the Microsoft 365 mail server but returns an error indicating that Business Central is not allowed to send email on behalf of the configured user. The cause is usually one of two things, and both are still relevant today.
Solutions
- Licensing. The trial edition of Business Central historically did not permit outbound email. If the user is on a trial or evaluation licence, the email option may be unavailable. Confirm the licence in the Microsoft 365 admin centre and move to a paid subscription where required.
- Mailbox and permissions. Send on behalf of the configured mailbox can be blocked by the account's own configuration. A reliable workaround is to send from a mailbox that does not have a Business Central licence assigned to it, or to grant the appropriate send permission to the sending account. With the Microsoft 365 connector, ensure the signed-in account has permission to send as the chosen address.
If email is part of a wider Business Central rollout, see our Dynamics 365 implementation page, or our guide on migrating legacy systems to Business Central.