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Microsoft 365 Blog
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High Volume Email Is Now Available in Exchange Online

JeremyCarlson's avatar
JeremyCarlson
Icon for Microsoft rankMicrosoft
Mar 31, 2026
Reliable email remains one of the most critical ways organizations communicate with employees at scale especially for operational, time‑sensitive messages like payroll notifications, security advisor...
Updated Mar 31, 2026
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alexandruliviunita's avatar
alexandruliviunita
Brass Contributor
Apr 01, 2026

I am currently evaluating adoption for this feature but have a few concerns:


1. It is unclear how we will be billed for this service.
Based on MC1243552 it is still free and will start being metered on June 1st.
Will it appears as an M365 pay as you go service that can be linked to an Azure Subscription, if so, when?

2. Will there be any change to the Service Limits published in : https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/high-volume-mails-m365#service-limits now that GA is announced?

3. OAuth guidance from : https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/oauth-high-volume-mails-m365 is vague about scoping the Entra ID App.
It advises we apply 'Office 365 Exchange Online' Mail.Send API Permissions to Entra ID App Registration, but provides no guidance on how Application Type permissions could be scoped to only be used for HVE Accounts.
Allowed Applications explains how the HVE Account can restrict which apps can use it, but how does this leave all the other mailboxes in our tenant?
We could restrict app scope via Application Access Policies, but this is a legacy feature and it does not scale well with HVE Accounts which cannot be added to MailEnabled Groups leading to 1:1 Application -> HVEAccount pairing and many Entra ID Apps and application access policies created.

  • Simone_Liebal's avatar
    Simone_Liebal
    Icon for Microsoft rankMicrosoft
    Apr 14, 2026

    alexandruliviunita​ thank you for the detailed questions! I'll respond to them one by one. 

    1. HVE will be billed through Microsoft 365 pay‑as‑you‑go and will require billing policies to be set up and linked to an Azure subscription. These billing policies can then be associated with the HVE service and assigned to individual HVE accounts. We will release the ability to configure billing policies for HVE in the coming weeks, so billing setup can be completed the ahead of time. Even if billing policies are configured for HVE prior to June 1st, usage will only start being metered from June 1st onward.
    2. The documentation reflects the up to date GA limits for High Volume Email. If those limits change in the future, updates will be reflected directly in the official documentation. 
    3. The Mail.Send application permission does not grant the ability to send email from all Exchange mail users. Following the described configuration from this page, only HVE Account type mail users will be able to send email, unless the application is explicitly authorized for other mail users through Exchange application access controls. We're in process of updating the documentation to reflect this more clearly - the update will be live soon. Thank you for your feedback regarding the documentation on OAuth for HVE!