Microsoft blocking emails sent via Graph API

[Dawid.Pekala]

hi all,
Just something of a warning - for those using Graph API for email (any recent solution)

As Microsoft was depreciating the simple authentication methods for email interaction we've moved to use of Graph API (via use of:
Microsoft Graph API - Outlook [DEPRECATED]

Blueprism		remove preview
Microsoft Graph API - Outlook [DEPRECATED] This asset exposes a subset of actions for interacting with Microsoft Outlook. View this on Blueprism >

and later
Microsoft 365 - Outlook

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Microsoft 365 - Outlook Supports working with Outlook, on Microsoft 365, without requiring Outlook to be installed locally. View this on Blueprism >

(we currently have a mix of usage of above - depending of use case (we'll be moving progressively to the latter solution as we rebuild our automations)).

I'm not sure if this is something recently introduced by Microsoft (the date of below KB would suggest it may be:(

(Fix email delivery issues for error codes 5.7.700 through 5.7.750 in Exchange Online

Microsoft		remove preview
Fix email delivery issues for error codes 5.7.700 through 5.7.750 in Exchange Online It's frustrating when you get an error after sending an email message. This topic describes what you can do if you see error codes 550 5.7.700 through 5.7.750 in a non-delivery report (also known as an NDR, bounce message, delivery status notification, or DSN). View this on Microsoft >

Over the weekend we came across a scenario where our - rather email-heavy - process has ran succesfuly, sending about 200 emails in space of 4 hours. Graph API accepted those and triggered the emails successfully (so no feedback from API), HOWEVER - all the emails sent resulted in an UNDELIVERABLE message (as per the above URL).

It seems that there are certain volume-related limitations to the Graph API that - when reached - trigger the exchange server (note-NOT the Graph API server) to reject any emails sent using the tenant/email.

What's worth pointing out is that - from what we can see - the same tenant :
- CANNOT send emails EXTERNALLY - when triggered via API (sending from the mailbox manually/using Outlook still works) (i.e. - it accepts API calls, but emails are NOT sent and Undeliverable message is being returned)
- CAN Still send INTERNAL emails using the affected mailbox (emails are coming through - so clearly the 'block' is happening on email server - when email  is being sent to an external recipient)
- CAN still send external emails using other mailboxes (I guess until the same thresholds are reached)

We are currently dealing - via our IT - with Microsoft to 'unblock' our email mailbox (and ideally remove the thresholds to prevent the same happening in future).

I thought that may be of interest for anyone with heavy email use.
(for visibility - i'm copying @ewilson and @RyanMatuszewski as they own the DX products mentioned above which may be affected)
​

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Dawid Pekala
IPA Lead
Lowell Group
Europe/London
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[JerinJose]

Thank you Dawid,

Thank you for the heads-up

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Jerin Jose
Technical Product Owner
EY
Asia/Kolkata ON
*"If you find this post helpful mark it as best answer, .*
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[ewilson]

@Dawid.Pekala,

I believe these are actually limitations imposed by Exchange Online and have nothing to do with Graph per se.​ Check out the link below:

https://learn.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits#receiving-and-sending-limits

Cheers,

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Eric Wilson
Director, Integrations and Enablement
Blue Prism Digital Exchange
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[Dawid.Pekala]

thank you @ewilson for your feedback.
This issue is still with our IT and they're investigating - so your insight is very valuable - i'll pass your link reference over to them.

Although my main point/warning is still valid - API will accept the 'send email' call (which for BP will look like the email has gone) - and the next stage (which - I'm happy to stand corrected - is Exchange Online) rejects the email.

Regards
Dawid Pekala

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Dawid Pekala
IPA Lead
Lowell Group
Europe/London
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[ewilson]

@Dawid.Pekala,

Yes, your point is still valid. Ideally Graph would respond with an error, but it seems the architecture doesn't support that most likely because the backend processing between Graph and Exchange is handled asynchronously. However, I was just looking through the Graph reference and there may be a way we can address this to an extent. It's not perfect, but I think it will work.​

Within Graph there are endpoints for reporting, and some of those endpoints include information about mailbox quota and usage. We could add support for some of those endpoints to allow you to retrieve your limits before sending large batches of emails.

Cheers,

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Eric Wilson
Director, Integrations and Enablement
Blue Prism Digital Exchange
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[Neel1]

although this thread is old but my current issue seems similar.

i have a situation where in outlook graph API is not able to send mail when RPA process is running in production. 

- there is no error showing in logs.

- we have no issue when process is running in lower env which makes me think  configuration of azure are all fine.

- not sure if limit is coming in picture as we have others bots sending mail fine.

what can be the issue

[ewilson]

Are you receiving a specific error response from the Graph call?

Cheers,

Eric

[Neel1]

Hello Eric - No, Not receiving any error.