When sending emails using Microsoft Graph API, what's the correct way to send more than 150 MB within 5 minutes?

Question

Background:

We have created 2 Azure single-tenant apps with the same set of permissions (Mail.Send & Mail.ReadWrite) within the same tenant. As per Graph API's documentation, we should be able to send emails of size upto 150 MB per email, through 1 app and 1 mailbox combination.

Link - https://learn.microsoft.com/en-us/graph/throttling-limits#outlook-service-limits

Problem:

Since the documentation mentions the combination, so ideally if we have 2 different Azure apps, then we should be able to send 2 separate emails of size 150 MB each (total 300 MB) within 5 minutes from the same mailbox.

But unfortunately, it does not work. We get a throttling error from Graph API when trying to draft 2nd email-

{
    "error": {
        "code": "ApplicationThrottled",
        "message": "Application is over its IncomingBytes limit."
    }
}

Question:

When the documentation mentions the combination, then why is the API not allowing to upload more than 150 MB (2 separate emails) in the same mailbox within 5 minutes using 2 different Azure apps?

Example:

Create Authorization token1 from App1.
Create a draft email in mailbox1 and upload a 140 MB file using the upload session.
Create Authorization token2 from App2.
Create another draft email in the same mailbox1 and upload a 140 MB file using the upload session. It fails at this step with the above error.

Raise a support ticket with MicroSoft. It may be that the linked details are not completely accurate, only MS would know for sure. — phuzi
– phuzi, Commented Jun 25, 2024 at 8:53
Already created one ticket, this question will allow me to know if anyone else faced the same issue and I can post updates about my MS ticket here. — Piyush Chugh
– Piyush Chugh, Commented Jun 25, 2024 at 8:57
You need to consider MIME bloat as well, while you attachment size maybe under 150 when you try to send it will bloat 137% en.wikipedia.org/wiki/Base64#MIME so 140MB is generally still going to be too large. — Glen Scales
– Glen Scales, Commented Jun 26, 2024 at 1:19
@GlenScales I have replicated the issue through Postman while uploading a 120 MB PDF in 2 separate emails in the same mailbox through 2 different apps. It's successful in app1 but fails with app2. — Piyush Chugh
– Piyush Chugh, Commented Jun 26, 2024 at 8:25
The documentation isn't clear on this (it's ambiguous) but my understanding of this is when you use Service principals (eg client credentials flow) this uses impersonation. So while your using different App's/Service principals the throttling budget is still being charged against the impersonated user. You would probably find that using a Delegate Token and an Application token against the mailbox would work (within the 5 minutes window) because they tend to be separate throttling budgets. It's done this way I believe to limit the service impact per mailbox. — Glen Scales
– Glen Scales, Commented Jun 27, 2024 at 0:07

Piyush Chugh · Accepted Answer · 2024-07-25 13:59:34Z

0

After creating a support ticket for Microsoft and following up with them for the last 1 month, the conclusion is that this is not allowed by design.

Here's the updated documentation to avoid any further confusion. Now both the API behaviour and documentation match with each other:

answered Jul 25, 2024 at 13:59

Piyush Chugh

3024 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

When sending emails using Microsoft Graph API, what's the correct way to send more than 150 MB within 5 minutes?

Background:

Problem:

Question:

Example:

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Background:

Problem:

Question:

Example:

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related