Hi @André Pereira ,
Based on your request, to get mail message attachment content you can use GET /me/messages/{id}/attachments/{id}/$value
, sample C# snippet.
var stream = await graphClient.Me.Messages["{id}"].Attachments["{id}"].Content
.Request()
.GetAsync();
Refer Example 6: Get the raw contents of a file attachment on a message
Hope this helps.
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