Microsoft Graph API - Send email with OAuth

Question

Hello,

We have an web app in which user's can authorize their own outlook account, either a basic outlook account or a Microsoft 365 Business account, to allow the app to send emails on their behalf. We have already set up the azure verified app to do this and everything is fine during the OAuth process.

For either basic or Microsoft 365 Busicess accounts, users are able to send emails via our app using the graph api and their oauth token. That is, our app is able to send emails on behalf of the user's own outlook account. However, for some users, the email is not sent despite not receiving an error from the Graph api. The email does show up on the user's sent folder in outlook but the email never gets received by the recipients.

What could cause this issue?

Regards,

John

Answer 1

Hi @NSoftware

Check the recipient's spam or junk folder to see if the emails are being filtered there. Sometimes, emails sent via the Graph API can trigger spam filters, causing them to be blocked or moved to the recipient's spam folder. This can happen even if the email appears in the sent folder without any errors.

Also, review the content of the emails to ensure they comply with best practices for avoiding spam filters.

If the above suggestions do not work, please open a support ticket with the Microsoft support team to get help from the API owner.

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Hope this helps.

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