Changes to Mailbox Setup in Microsoft 365 & Business Central

  • Published on Feb 16, 2026
  • 2 minute(s) read
  • Mark Fugett
 Prev Next

Microsoft is retiring Basic SMTP authentication at the end of December 2026, meaning organisations using Business Central will need to ensure email sending is configured through Microsoft 365 Shared Mailboxes instead of legacy SMTP methods. This article outlines the requirements, setup steps, and admin actions needed to ensure continued email functionality.

Note:

Elite Dynamics provides this setup guidance, but does not offer direct support for configuring email accounts. Please also note that if you use another email provider for sending emails out, they may not be affected by the changes Microsoft are implementing.

Why Shared Mailboxes

Shared Mailboxes allow multiple users to send outbound emails from Business Central using a centralised mailbox identity. With Microsoft’s retirement of Basic SMTP, this method becomes the supported approach for secure and compliant email delivery.

Requirements

Setting up Shared Mailboxes requires the appropriate administrative roles in the Microsoft 365 Admin Centre. Only users with these permissions can create shared mailboxes and assign users to them so that they can send emails “as” the shared address.

How to Set Up a Shared Mailbox in Business Central (Step-by-Step)

  1. Add a New Email Account in Business Central

    1. Go to Email Accounts

    2. Select New

    3. Choose Add an Email Account.

  1. Start the Setup Wizard

  1. Select Next to begin.

  2. Choose Email Provider Select Microsoft 365 (Use Microsoft 365 Mailboxes) — the default and correct choice for Shared Mailboxes. Then click Next.

  1. Enter the Mailbox Details, providing the following:

    1. Account Name

    2. Email Address

  2. This link is provided for more details on Shared Mailbox permissions: Shared mailboxes in Exchange Online | Microsoft Learn

  3. Lastly, confirm your configuration:

    1. The final screen confirms your details and allows you to:

      1. Set the acount as default (optional)

      2. Adjust Rate Limit per Minute

You can then test the connection using Send test email before finishing.

Admin Steps in Microsoft 365 (Step-by-Step)

  1. First step is to create the Shared Mailbox:

    1. In the Microsoft 365 Admin Centre, navigate to:

      1. Teams & Groups → Shared mailboxes → Select Add a shared mailbox

      2. The name that shows here is what the reciepents will see and you will see the actual email address.

      3. If you have more than one domain you can change this here.

  1. Assign Permissions

  2. Once created it can take a moment for the Mailbox to appear so refresh the page.

  3. Now click the new mailbox name

  4. Open Manage mailbox permissions

  5. Add users to Send as permissions so they can send emails from Business Central using this identity.

Microsoft may take a short time to process permission updates, after which you should test sending from Business Central.

Microsoft Blog Article: Update on Deprecation Timeline