How to set both List-Unsubscribe-Post and List-Unsubscribe headers for Microsoft Graph API?

Question

How to set both List-Unsubscribe-Post and List-Unsubscribe headers for Microsoft Graph API?

GZ 0

Hi,

I am using the Microsoft graph API to send emails. I need to be able to set two headers List-Unsubscribe-Post and List-Unsubscribe to allow receivers to automatically unsubscribe. I saw https://learn.microsoft.com/en-us/answers/questions/1509500/how-to-provide-list-unsubscribe-header-using-micro already but I need to put two headers and I do not understand where the 'id: 'String 0x1045' in the solution comes from.

Any help would be very much appreciated. My code is:

SendMailPostRequestBody sendMailPostRequestBody = new com.microsoft.graph.users.item.sendmail.SendMailPostRequestBody();

com.microsoft.graph.models.Message message = new Message();
message.setSubject(emailDetails.getSubject());
ItemBody body = new ItemBody();
body.setContentType(BodyType.Html);
body.setContent(emailDetails.getHtmlBody());
message.setBody(body);


LinkedList<Recipient> toRecipients = new LinkedList<>();
Recipient recipient = new Recipient();
EmailAddress emailAddress = new EmailAddress();
emailAddress.setAddress(emailDetails.getTo());
recipient.setEmailAddress(emailAddress);
toRecipients.add(recipient);
message.setToRecipients(toRecipients);

1 answer

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Answer 1

Pardha Saradhi Reddy Jaladi-MSFT 475 Microsoft External Staff

Hello GZ,

Thank you for reaching out to Microsoft Support!!

The id: 'String 0x1045' mentioned in the example you provided corresponds to a custom header that is specified in the MIME format of the email. It is not a specific value that you need to derive or generate, it simply represents an arbitrary identifier for the custom email header being added. These kinds of header identifiers are typically used when constructing MIME email data via APIs such as Microsoft Graph. It isn't directly relevant for Graph API calls.

Based on what you’ve provided, you are correctly setting up the email subject, body, and recipients using the Microsoft Graph Java SDK. To include the List-Unsubscribe and List-Unsubscribe-Post headers, you'll need to utilize the internetMessageHeaders property of the Message object.

This Microsoft Graph API documentation, confirms that the internetMessageHeaders property can be used to add custom headers when creating a message. While it doesn't explicitly mention List-Unsubscribe or List-Unsubscribe-Post, it does state that custom headers can be added to a message during its creation. This aligns with the use case of including these headers for unsubscribe functionality. User's image
Hope this helps.

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

Pardha Saradhi Reddy Jaladi-MSFT 475 Reputation points Microsoft External Staff

2025-03-26T20:56:43.3533333+00:00

Hello GZ, Is there anything else I can help you with regarding this issue? If you still need further help, please feel free to let me know. If your question has been solved, then you can click "Accept Answer", which may help members with similar questions. Thank you very much.

Ippei Onuki 0

I was able to add the List-Unsubscribe header to email headers using SingleValueLegacyExtendedProperty, referencing the URL below: https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxprops/f6ab1613-aefe-447d-a49c-18217230b148

$listUnsubscribeProperty = new Model\SingleValueLegacyExtendedProperty();
// PidTagListUnsubscribe: Property ID 0x1045, Data type: PtypString (0x001F)
$listUnsubscribeProperty->setId('String 0x1045');
$listUnsubscribeProperty->setValue('<' . $url . '>');
$this->listUnsubscribeHeader = [$listUnsubscribeProperty];
$this->sendMessage = new Model\Message();
if ($this->listUnsubscribeHeader !== null) {
    $this->sendMessage->setSingleValueExtendedProperties($this->listUnsubscribeHeader);
}
// ... sending process omitted

When I sent the email, the List-Unsubscribe header was added to the email headers.

List-Unsubscribe: <https://example.com/>

However, when I viewed the received email in Gmail, the "Unsubscribe" link was not displayed.

So I tried adding the List-Unsubscribe-Post header as a custom header using InternetMessageHeader. Since InternetMessageHeader requires the X- prefix, I implemented it as follows:

$listUnsubscribeProperty = new Model\SingleValueLegacyExtendedProperty();
$listUnsubscribeProperty->setId('String 0x1045'); // PidTagListUnsubscribe: Property ID 0x1045, Data type: PtypString (0x001F)
$listUnsubscribeProperty->setValue('<' . $url . '>');
$this->listUnsubscribeHeader = [$listUnsubscribeProperty];
$this->sendMessage = new Model\Message();
if ($this->listUnsubscribeHeader !== null) {
    $this->sendMessage->setSingleValueExtendedProperties($this->listUnsubscribeHeader);
}

$listUnsubscribePostHeader = new Model\InternetMessageHeader();
$listUnsubscribePostHeader->setName('X-List-Unsubscribe-Post');
$listUnsubscribePostHeader->setValue('List-Unsubscribe=One-Click');            
$this->listUnsubscribePostHeader = [$listUnsubscribePostHeader];
if ($this->listUnsubscribePostHeader !== null) {
    $this->sendMessage->setInternetMessageHeaders($this->listUnsubscribePostHeader);
}
// ... sending process omitted

When I viewed the received email in Gmail again, the "Unsubscribe" link was still not displayed. The email headers looked like this:

List-Unsubscribe: <https://example.com/>
x-list-unsubscribe-post: List-Unsubscribe=One-Click

It appears that Gmail doesn't recognize X-List-Unsubscribe-Post and only recognizes List-Unsubscribe-Post. However, Microsoft Graph API's InternetMessageHeader requires the X- prefix. Therefore, it's currently impossible to add both the List-Unsubscribe header and the List-Unsubscribe-Post header using Microsoft Graph API! Are there any other methods available? With Gmail and Yahoo strengthening their spam countermeasures, urgent action is needed. It's very regrettable that Microsoft Graph API cannot properly add List-Unsubscribe headers.

Please let me know if there are any other methods available.

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How to set both List-Unsubscribe-Post and List-Unsubscribe headers for Microsoft Graph API?

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