SMTP Email sending using Multi-Tenant Environment

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Posted on by Vaseem Ali

Hi,

I have a situation where the customer has several tenants as follows:

Tenant A - used for managment of Office 365, Exchange, etc.

Tenant B - used for Business Central.

The users from Tenant A, have been invited as Guests to Tenant B and given licenses to Business Central.

When we have attempted to setup SMTP emails this doesn't seem to work due to authentication issues. We get the following error:

The SMTP server rejected the authentication request, as the authentication data is incorrect. Verify that your Username and Password are correct and that the SMTP server supports the specified authentication type (OAuth 2.0). SMTP error code: 535.

I have done some research online but the only answers we have found are to do with on-premise installations not on the cloud.

Has anyone done this before? If so, what setup needs to be in place to make this possible please?

Thanks,

Vaseem

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Kelsey 18 on at

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SMTP Email sending using Multi-Tenant Environment

Vaseem

Thank you very much for sharing your findings. Our client is facing the similar scenario. I also tested and confirmed basic authentication works. Since OAuth 2.0 is a more secure way, I would like to find out if it is possible to configure SMTP with OAuth 2.0 for a multi-tenant environment. May I know if you may be aware of any update from Microsoft and see if OAuth 2.0 can be used?
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Vaseem Ali 79 on at

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SMTP Email sending using Multi-Tenant Environment

I can confirm I have this working now.

The setup required is a follows:

1. In a Multi-tenant environment you have to use SMTP. The Office 365 and Shared Mailbox options will not work.

2. When setting up the SMTP you need to use Basic Authentication. This is obviously less secure so not all customers will want to do this.

3. When using this option you need to set a Password. The password is not your normal Office 365 password but an App Password. This can be setup in your Office 365 account.

There maybe other considerations here for the Office 365 tenant as there could be Group Policies, Security Groups, etc blocking the Basic Authentication. However as long as there is nothing stopping this it will send.

I believe this option would also work in those scenarios where a users do not have Office 365 accounts, such as Gmail, Yahoo, etc.
Vaseem Ali 79 on at

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SMTP Email sending using Multi-Tenant Environment

Thanks will give shared mailboxes a go.

Do you have any recommendations on what authentication we should use for the Shared Mailboxes?
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Inge M. Bruvik 32,718 Moderator on at

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SMTP Email sending using Multi-Tenant Environment

I think it should be possible to get it to work.

What I first would do is to try to use a shared mailbox and see if you get that to work if you already have not tried that?
Vaseem Ali 79 on at

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SMTP Email sending using Multi-Tenant Environment

Hi,

Not sure this is the answer as the users are Guests. They aren't Delegated Admin nor are they External Accountants. We also need to consider he scenarios whereby they don't have Office 365, what if they had Gmail, Yahoo, etc. How would that work?

I've been doing some research online and found this: Sending email via SMTP in Business Central (online and on-premise) – Kauffmann @ Dynamics 365 Business Central

This suggests it could work with App Passwords and Basic auth still but I've yet to get it working.

Thanks,

Vaseem
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YUN ZHU 62,477 Moderator on at

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SMTP Email sending using Multi-Tenant Environment

Hi, unfortunately, this is mentioned in Microsoft's documentation.

External users, such as delegated admins and external accountants, cannot use these extensions to send email messages from Business Central.

https://learn.microsoft.com/en-us/dynamics365/business-central/admin-how-setup-email#add-email-accounts

Hope this helps.

Thanks.

ZHU