High Volume Email Account for Exchange Online

4 June 2025

Why did Microsoft implement HVE accounts for Exchange online customers?

Microsoft plans to deprecate SMTPTLS with basic authentication in March 2026 (originally September 2025) for SMTP Clients using the Exchange online service. Refer to Exchange team blog Exchange Online to retire Basic auth for Client Submission (SMTP AUTH) | Microsoft Community Hub

Extract from the Microsoft article below:

Microsoft identified the need to provide ongoing support for devices and applications that do not support OAuth2.   

Microsoft Web Site information how to setup HVE accounts

Microsoft information can be found at Manage high volume emails for Microsoft 365 in Exchange Online Public preview | Microsoft Learn

msXfax and HVE accounts

To set up a HVE account for use with msXfax the following is a guide how to do this.

A single HVE Account can be created for use by all FAX servers. This is important because there is a limitation of 20 HVE accounts per organisation as at (April 2025). 

From Exchange online admin centre - create a HVE account like the example below

Your Exchange online administrator will need to use Powershell to setup the required authentication policy.

BNS assumes that the administrator has the correct level of knowledge with Exchange online. Contact Microsoft if you have any issues with or creating HVE accounts or assigning permissions.   

• Using Powershell
• Connect-Exchangeonline
• Create an authentication policy to allow HVE accounts to use basic authentication with SMTP AUTH

New-AuthenticationPolicy -Name "High Volume Email" -AllowBasicAuthSmtp

Set-User FAXHVE -AuthenticationPolicy "High Volume Email"

• Record the HVE account details in your password database

Changing msXfax to use a HVE account

If there is a requirement to implement a HVE account to allow SMTP AUTH for the fax server to send SMTP messages to Exchange online; the following settings are required in the msXfaxboot.ini file. 

The ini file is located in the :Program FilesBNS GroupmsXfax EnterprisePrograms  folder. 

• STOP the fax services using the FAXSTOP command or STOP the services from the msXfax dashboard.
• Edit the :Program FilesBNS GroupmsXfax EnterpriseProgramsmsXfaxboot.ini file using notepad

• change the end point SMTP address to smtp-hve.office365.com 
• change the smtp user name and password for the new hve account. 
• Set the value of DMZ-Outbound-smtpPasswordEncrypted-int=0
• Set the value of DMZ-Inbound-smtpPasswordEncrypted-int=0 

• After the change has been made to the msXfaxboot.ini file, save the file and close the file. 

• START the fax services using the FAXSTART command or start the services from the msXfax dashboard.