Enable SMTP authentication Office 365 shared mailbox

There are many reasons you may want to setup a shared mailbox, but the one we see the most often has to do with licensing.  Shared Mailboxes in Microsoft 365 do NOT require a license, although all users that connect to that shared mailbox DO require a license.

Note that a Exchange Online Kiosk License is insufficient to access a Microsoft Office 365 Shared Mailbox; you need a full license.

Also, there are many that will tell you it is not possible to log into a Shared Mailbox directly, but we will show you how to easily get around that.

1. Access the Microsoft 365 Exchange Admin Portal
   1. Surf to portal.office.com, sign in, click the A icon for the ADMIN portal on the left rail
   2. Click SHOW ALL… (in the left menu) then click EXCHANGE
      Alternately you can surf directly to admin.exchange.microsoft.com 
2. Expand RECIPIENTS
3. Click MAILBOXES
4. Click ADD A SHARED MAILBOX
5. Enter the DISPLAY NAME, EMAIL ADDRESS and ALIAS you want
6. Click the SAVE button
7. Click on the Shared Mail box you just created
8. Click MANAGE MAILBOX DELEGATION
9. Click EDIT on both READ AND MANAGE and SEND AS and add whoever you want to have access to that account

If you want to access a Shared Mailbox directly using Outlook or Outlook Webapp, you need to assign it an Exchange license.

If you want to use a Shared Mailbox as an SMTP relay (i.e. you want a program like phpBB to send email through them) you can’t.  See this Microsoft thread on Authenticated SMTP with Shared Mailboxes.

How to create App Password for Office 365 SMTP Server

IntroductionIf you have MFA enabled for your Exchange Online mailbox in Office 365 or Microsoft 365, then you can’t use your main account password to authenticate the Office 365 SMTP settings. You will need to create a separate App Password and use it in the SMTP settings in AutoDocMail/AutoMailMerge plug-ins. Typically, if sending of the messages fails with the following or similar error message, then most likely you need to use an App Password.

An error occured sending the message, Error:80048011
Description:Unexpected AUTH LOGIN password response, Last Response: 535 5.7.3 Authentication unsuccessful [BLAPR03CA0069.namprd03.prod.outlook.com]

SMTP AuthenticationYou can skip this step if you know for sure that you can send emails using SMTP Authentication from your email account. Make sure SMTP AUTHENTICATION is enabled for your online email account: https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission. Create App Password1. Sign in to Office 365.2. Choose Settings > Office 365.3. Choose Security & Privacy > Additional Security Verification. You’ll only see this option if your admin has set up multi-factor authentication for your organization. If you don’t see this option, contact your Office 365 admin and tell them to turn on multi-factor authentication. 4. Choose Update my Phone Numbers Used for Account Security. You should see the following screen: 5. At the top of the page, choose App Passwords.6. Choose Create to get an app password.7. If prompted, type a name for your app password, and click Next.8. Push copy password to clipboard button. You won’t need to remember this password. Now open email settings in AutoMailMerge or AutoDocMail and use this password for SMTP connection parameters instead of your main account password. You can have more than one app password for your Office 365 account, for example, one for AutoMailMerge and another one for a different application. To generate another app password, see Create an app password.Office365 SMTP Server Settings The settings below should work for everyone with an Office 365 or Microsoft 365 plan that has Exchange Online. Use these settings in AutoMailMerge/AutoDocMail for the email server parameters.

• SMTP Server address: smtp.office365.com
• SMTP Port number: 587 (with TLS)
• Authentication: Required
• Username: (your Office 365 email address) ()
• Password: (your Office 365 password)

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