Using MS Graph to send email from singe predefined/pre-set mailbox within .net web application

Question

Using MS Graph to send email from singe predefined/pre-set mailbox within .net web application

Julian Cram 25

We need our application to send emails via MS Graph using a set single mailbox.

I have the following, but this is not working, with the following: 'Exception of type 'Microsoft.Graph.Models.ODataErrors.ODataError' was thrown'.

Digging into the details indicates an 'Access is denied' error.

Appropriate App registration in Azure was set-up with MS Graph Mail.Send permissions added.

I've tried the 'generic' email (no-reply@) and my own (the latter of which I know is included as a member of the app in Azure).

There appears to be a lack of documentation for using MS graph with .net, and/or a lack of documentation around sending emails using a pre-set mailbox (rather than asking the user for credentials).

Having pieced the below code together from a number of sources, I believe I need to retrieve and then pass with the sendmail.postAsync a token, but I'm stuck at this point.


 ClientSecretCredential credentials = new ClientSecretCredential(tenantId, clientId, mySecret, new TokenCredentialOptions() { AuthorityHost = AzureAuthorityHosts.AzurePublicCloud });

    GraphServiceClient client = new GraphServiceClient(credentials);

    var eUser = client.Users("******@domain.com");

    Await(eUser.SendMail.PostAsync(new Users.Item.SendMail.SendMailPostRequestBody() { Message = email, SaveToSentItems = true }));

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5 answers

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Answer 1

Anonymous

Hello Julian Cram,

Thanks for reaching out. You can find a C# SendMail Graph API example here. Replace the line:

var requestBody = new Microsoft.Graph.Me.SendMail.SendMailPostRequestBody

with :

var requestBody = new Microsoft.Graph.Users.Item.SendMail.SendMailPostRequestBody

and line:

await graphClient.Me.SendMail.PostAsync(requestBody);

with

await graphClient.Users[UserID].SendMail.PostAsync(requestBody);

and change the emails To and From address and subject.

Some of the properties are required such as To Address for example and cannot be omitted.

If the reply is helpful, please click Accept Answer and kindly upvote it. If you have additional questions about this answer, please click Comment.

Thanks.

Julian Cram 25 Reputation points

2023-06-06T08:32:37.42+00:00

Thanks for answering.

I had already reviewed the document to which you linked, and made the code changes you suggest (see original code snippit).

I still get an 'Access is Denied' error (403). I believe this is because I am missing out a step concerning a token.

The problem with the examples in the document you linked is that there is no information on how 'requestAdapter' is defined.

As you can see from my code snippit, I am currently defining a new GraphServicesClient with a ClientSecretCredential. Is this correct? Can you point me to where/how I can retrieve a token and how that should be passed as part of the SendMail request? I have found many different examples of retrieving a token, using many different approaches, but none of them are for sending email.

Answer 2

Julian Cram 25

Removed as it should have been a comment on the first answer.

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Answer 3

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Answer 5

Hi All,

i have tried the same but I am getting an error always:

HResult=0x80131500

Message=One or more errors occurred. (OnBehalfOfCredential authentication failed: AADSTS50013: Assertion failed signature validation. [Reason - Key was found, but use of the key to verify the signature failed., Thumbprint of key used by client: 'XXXXXXXXXXXXX', Found key 'Start=02/08/2024 17:02:53, End=02/08/2029 17:02:53', Please visit the Azure Portal, Graph Explorer or directly use MS Graph to see configured keys for app Id '00000000-0000-0000-0000-000000000000'. Review the documentation at https://docs.microsoft.com/en-us/graph/deployments to determine the corresponding service endpoint and https://docs.microsoft.com/en-us/graph/api/application-get?view=graph-rest-1.0&tabs=http to build a query request URL, such as 'https://graph.microsoft.com/beta/applications/00000000-0000-0000-0000-000000000000']. Trace ID: YYYYYYYY Correlation ID: zzzzzzzzzzzzz Timestamp: 2024-03-14 12:01:44Z)

Source=System.Private.CoreLib

StackTrace:.........

Can some one please help what is the issue here.