Connect a Microsoft 365 or Outlook mailbox

This guide connects a Microsoft 365 or Outlook work mailbox as a sending account. Argorant uses its own Microsoft app, so there is nothing to register in Azure and no password is stored: the mailbox signs in with Microsoft and can revoke access there at any time.

Before you start

• The mailbox must be a work or school account on Microsoft 365. Personal @outlook.com and @hotmail.com addresses are not accepted as senders.
• For steps 1 to 5 you need a Microsoft 365 admin, or someone with the Exchange admin role. It is one change per user.

Step 1: allow authenticated SMTP and IMAP for the user

1. Login to your Microsoft 365 Admin Center.
2. Click on your Active Users.
3. Click onto the user you want to connect.
4. A fly out will appear. Click on the Mail tab and then click on Manage email apps.
5. Make sure the Authenticated SMTP and IMAP options are enabled.
6. Click on Save changes. Microsoft can take up to 30 minutes to apply this.

Step 2: connect the mailbox in Argorant

1. In Argorant, open Inboxes in the left menu and click Add accounts.
2. Choose Connect existing, then Office 365 / Outlook.
3. Click Login and sign in with the mailbox you want to connect. Do not sign in with the admin account unless the admin mailbox itself should send.
4. You come back to Inboxes with the mailbox listed. Turn on warm-up before you send at volume.

If Microsoft says "Need admin approval"

Some tenants block third-party apps until an admin has consented once. The Microsoft step in Argorant contains an approval link: a Microsoft 365 admin opens it, accepts for the whole organisation, and from then on every mailbox on that tenant connects with a plain Login.

Troubleshooting

• Sign-in works but the mailbox shows Disconnected: Authenticated SMTP was not enabled, or the change has not propagated yet. Wait 30 minutes and use Reconnect.
• "This account is not a work account": personal Microsoft accounts cannot be senders. Use a Microsoft 365 mailbox on your own domain.
• Shared mailboxes: connect them with a licensed user that has Send As rights, then set that user as the sender.