What is the High-Volume Email (HVE) Service in Microsoft 365?
Microsoft 365 has introduced the High-Volume Email (HVE) service as an option for mass email sending. The service is currently in public preview and is designed for organizations that need to send larger volumes of emails.
In this blog post, you'll learn everything about the prerequisites, limitations, use cases, setup, and analysis of HVE in Microsoft 365.
Prerequisites
For the HVE service to function properly, the following conditions must be met:
Security Defaults: Security Defaults must be disabled.
SMTP Authentication: SMTP Authentication must be enabled in the tenant, as it is required for HVE.
Limitations and Restrictions
When using HVE, the following restrictions apply:
Recipient Limit: Up to 100,000 recipients per 24 hours, with a maximum of 2,000 external recipients per 24 hours.
Purpose: Microsoft states, “The HVE service is primarily intended for internal mass communication.”
Number of HVE Accounts: A maximum of 20 HVE accounts.
Message Limit: Up to 50 recipients per message.
Licensing: HVE accounts are special email user accounts and do not require licensing.
When Should I Use HVE?
The HVE service is ideal for the following scenarios:
Automated Emails: Notifications, alerts, reports.
Mass Emails: Marketing campaigns, newsletters (as long as the limit of 2,000 external recipients per 24 hours is not exceeded).
Transactional Emails: Invoices, order confirmations, delivery status updates.
Practical Example
A company that regularly sends invoices or transactional emails in high volumes using Sage can utilize the HVE service to improve delivery reliability. If Exchange Online is already in use, there’s no need to acquire an additional third-party service.
Setting Up the HVE Service
Steps for Configuration:
Open the Exchange Admin Center.
Navigate to Mail Flow > High-Volume Email (Preview).

Create a new HVE account.
Note: The account name should reflect the application or service used to send the emails. For example, the account for Sage should be named
HVE_SAGE
to facilitate identification.

Conditional Access for HVE Accounts
When an HVE account is created, an identity is automatically established in Entra ID. This identity must be integrated into the Conditional Access framework:
Assign a Persona Group: Allows basic communication.
Maximize Restrictions: Limit account usage to its defined purpose to prevent misuse.
Reports and Analysis
You can monitor the performance and usage of HVE accounts through the Exchange Admin Center:
Navigate to Reports > Mail Flow > High-Volume Email (Preview).
Analyze the number of emails sent using specific HVE accounts.
Typical metrics include:
Number of emails sent per account.
Failed delivery attempts and their reasons.
Delivery speed and duration.
Frequency of usage by day or hour.
Conclusion
The High-Volume Email service in Microsoft 365 provides businesses with an ideal solution for bulk email sending. By adhering to the prerequisites and limits, organizations can handle high email volumes securely and efficiently without impacting regular communication. Leverage HVE for your automated processes to enhance your business efficiency.