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BC SaaS, oauth2 SMTP config error

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Posted on by NAVBC

Error : Unable to get SMTP Account password

Note: in screeshot replace with x.com, the email have valid license (office 365,d365 premium)

grant consent is done

api permission is given by following

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

also when i try to more username in smtp config

error is :

also , tried with "Use custom OAuth 2.0 settings" enabled , granting consent too .. same errors.

can anyone advise ?

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Dynamics 365 Business Central

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Aman Kakkar 2,977 Super User 2026 Season 1 on at

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Hey,

Confirm again if the user that has the license is the same user that you are using for SMTP configuration.

Delete all other email accounts and try re-creating the email account with the following steps -

Select SMTP and add the following details -

Enable Custom App Registration -

Add Custom App details and grant the Consent -

Click on Edit Account and turn off the Custom OAuth 2.0 Settings -

Now, try sending the test email -

Also, if you want to use another account to send the emails on behalf, then you need to enable Send As boolean in the M365 Admin portal and add the users that can send the email on behalf of the email account that is setup.

Do mark as verified if this helps.

Aman K

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OussamaSabbouh 11,612 Super User 2026 Season 1 on at

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Hello ,

This issue isn’t about licenses or missing permissions — it’s caused by a mismatch between how Business Central sends email via SMTP OAuth and how Exchange Online enforces “Send As” rules. When BC shows “Unable to get SMTP Account password”, it actually means OAuth token acquisition failed, often because the mailbox used in SMTP is not the same mailbox as the sender or Exchange blocks it with 5.2.252 Send As not permitted. Enabling Authenticated SMTP and granting Graph permissions alone won’t fix this. The reliable, supported solutions are either (1) use the exact same mailbox for SMTP username and sender (no aliases/shared mailboxes), or (2) avoid SMTP entirely and use the Microsoft 365 Email connector, which sends via Graph and bypasses all SMTP/OAuth/Send As complexity. Re-consenting, toggling custom OAuth, or adding more API permissions will not resolve it.

Regards,
Oussama Sabbouh

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NAVBC 45 on at

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Hi Oussama Sabbouh

Thank you for the response...

for this (1) use the exact same mailbox for SMTP username

Yes, we are using the exact same , using basic auth e-mail can able send, but using oauth2 not working

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NAVBC 45 on at

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thanks @Aman Kakkar the worked after add the users that can send the email on behalf of the email account that is setup.

Once the account is added, the changes may not take effect immediately. The backend may require some time to apply the updates—this could take up to an hour or, in some cases, up to a day. depends

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Aman Kakkar 2,977 Super User 2026 Season 1 on at

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@NAVBC,

Please mark the answers as verified to close this forum.

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