Hi @Mensina Kary
As per the documentation, yes you can retrieve your personal Microsoft account messages using Graph API.
The error occurs when you do not have required permissions in your token. To get mails you need to consent Mail.ReadBasic, Mail.Read permissions.
To add these permissions, go to modify tab and consent these permissions. Please refer to the below sample screenshot:
Reference documentation : https://learn.microsoft.com/en-us/graph/api/user-list-messages?view=graph-rest-1.0&tabs=http#permissions
Hope this helps.
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