Filter Microsoft Graph Webhook Subscription by Email Subject Prefix

Question

I am working with Microsoft Graph webhooks for Outlook mail and would like to know if it’s possible to filter notifications at the subscription level based on the email subject.

Requirement I only want my system to receive webhook notifications for emails where the subject starts with:

"Quote of the Day" 

At the moment, the subscription notifies my endpoint for all incoming emails, and I then have to filter them after receiving the notification. I would like to avoid this extra processing if possible.

Question

Is there a way to apply a subject-based filter directly in the subscription resource (for example using $filter) so that only matching emails trigger notifications?

Example

Current subscription request (simplified):

POST https://graph.microsoft.com/v1.0/subscriptions

{
  "changeType": "created",
  "notificationUrl": "https://myapp.com/notifications",
  "resource": "me/mailFolders('Inbox')/messages",
  "expirationDateTime": "2026-02-17T10:00:00Z",
  "clientState": "secretValue"
}

What I’m looking for is something conceptually like this (if supported):

"resource": "me/mailFolders('Inbox')/messages?$filter=startswith(subject,'
Quote of the Day
')"

Clarification Needed

Does Microsoft Graph support subject-based filtering in webhook subscriptions?

If not, is server-side filtering the only supported approach after receiving notifications?

Are there any recommended patterns or workarounds for this scenario?

Any guidance or official documentation references would be greatly appreciated.

Answer 1

Microsoft Graph does not currently support filtering notifications at the subscription level based on the email subject. The $filter query parameter can be used to refine notifications, but it does not allow for filtering based on the subject of incoming emails in the way you described. Therefore, you will need to handle filtering on the server-side after receiving the notifications for all incoming emails.

This means that your current approach of subscribing to all messages and then filtering them based on the subject after receiving the notifications is the only supported method for this scenario.

For more information on how to set up notifications and the limitations of subscriptions, you can refer to the Microsoft Graph documentation on change notifications.

---

References:

• Change notifications for Outlook resources in Microsoft Graph
• Microsoft Graph API change notifications

Answer 2

You cannot. While some of the resources that are supported for subscriptions/notifications do support the $filter parameter, the messages resource does not. You will have to do the filtering client-side.