在统一列表中使用 Microsoft Graph SDK 获取所有 Email 标头？

Question

I'm using Microsoft Graph to get information from a specific account's inbox. That account has multiple email aliases. However, even after I $select query the InternetMessageHeaders property, it does not include the alias the email was sent to.

I found out that if I also select and expand the query using singleValueExtendedProperties , I get what I need, but now I'm missing some headers that are present in InternetMessageHeaders . It also comes back in a giant blob of text that doesn't seem too straight forward to parse. If I could somehow parse this blob of text into a key:value map, I could just merge both these values and call it a day, but I don't know if that's possible. I was hoping it might be possible with multiValueExtendedProperties , but I don't think that's an intended use for it.

I'm using Microsoft Graph's SDK for .NET (currently using 4.0.0) and this is what I have so far to get all the emails:

public async Task<List<Message>> PollEmails() {
    var completeList = new List<Message>();

    var messagesRequest = await graphClient.
        Users[GraphOptions.AccountId]                                               // Email account ID
            .Messages                                                               // All Emails
            .Request()                                                              // Create request w/ authorization & headers needed
            .Select("internetMessageHeaders,singleValueExtendedProperties")         // Additionally, select the email's headers
            .Expand("singleValueExtendedProperties($filter=id eq 'String 0x007D')") // Without this filter, we cannot tell which email alias was used in the To: field
            .Top(100)                                                               // Get emails in batches of 100 (default is 10)
            .GetAsync();                                                            // Run request and await results

    completeList.AddRange(messagesRequest);

    // Results are paginated, so keep getting all the results until there are no more pages
    while (messagesRequest.NextPageRequest != null) {
        messagesRequest = await messagesRequest.NextPageRequest.GetAsync();
        completeList.AddRange(messagesRequest);
    }

    return completeList;
}

Message.InternetMessageHeaders has most of the headers I need, and the rest are in Message.SingleValueExtendedProperties , but there's no easy way to merge the two into one list without duplicate headers.

I could just blindly loop through InternetMessageHeaders and append $"{Name}: {Value}" to the SingleValueExtendedProperties value, but I'll end up with duplicate headers. I could just search the string for the key before I append it, but that just feels like a hack.

Is there an official way to get every single header using Microsoft Graph's SDK?

Thank you,

EDIT

Here's a list comparing the headers in case anyone is curious about what I meant with headers starting with "ARC-*" :

This is an example (from the API) of what I get back from InternetMessageHeaders in JSON format: https://pastebin.com/Bdk35C5q

This is what I get back from SingleValueExtendedProperties in plain text: https://pastebin.com/N7c0JLB6

---

Related questions that don't answer my question:

Microsoft Graph: How to get the alias from an email message? - How to get the alias email used via singleValueExtendedProperties - doesn't include headers starting with ARC-*

Get message using Graph missing some InternetMessageHeaders - Get "complete" list of headers, again via singleValueExtendedProperties - again, doesn't include headers starting with ARC-*

https://docs.microsoft.com/en-us/answers/questions/673767/how-to-read-all-internet-message-headers-of-an-ite.html - Asking exactly what I'm asking but never got a response.

Answer 1

Turns out Outlook just isn't consistent with which headers each email has. So, in this case, the singleValueExtendedProperties was actually what I needed.

What I didn't realize I was asking for was I needed MAPI properties, as Dmitry pointed out (thank you for clarifying).

In case anyone else stumbles on this question before the other ones I found, here's what you need to do to access the MAPI properties:

API:

GET https://graph.microsoft.com/v1.0/users/{id | userPrincipalName}/messages/{id}?$expand=singleValueExtendedProperties($filter id eq 'String 0x007D')

SDK:

// Since `$select` only returns the properties you specify and the only way to get this property is with both `$select` and `$expand`, you have to manually select all the properties you want. Thanks, Microsoft.
var selectProperties =
    "id,subject,receivedDateTime,sentDateTime,from,toRecipients,ccRecipients,bccRecipients," +
    "replyTo,internetMessageHeaders,singleValueExtendedProperties,bodyPreview,body,hasAttachments," +
    "sender,categories,parentFolderId,conversationId,conversationIndex,isDeliveryReceiptRequested," +
    "isReadReceiptRequested,isRead,isDraft,webLink,inferenceClassification,flag";

// Get user's emails (Requires permission Mail.Read) - 
var messagesRequest = await graphClient.
    Users[AccountId]                                                            // Replace this with account ID
        .Messages                                                               // All Emails (or specify specific email via ["emailId"]
        .Request()                                                              // Create request w/ authorization & headers needed
        .Select(selectProperties)                                             // Select all the specified properties
        .Expand("singleValueExtendedProperties($filter=id eq 'String 0x007D')") // Select MAPI property Transport Message Headers to get the original `To:` email
        .Top(100)                                                               // Get emails in batches of 100 (default is 10)
        .GetAsync();

For a complete list of MAPI properties, see this page . For the specific MAPI property used in this example, see this page .

Can you get PR_TRANSPORT_MESSAGE_HEADERS 0x007D from the.Net Microsoft Graph API?