Set Up High Volume Email in Microsoft 365 for Staffbase Platform

Microsoft 365 is an alternative to standard relay that lets you send large volumes of email to internal mailboxes without hitting per-mailbox sending limits. Staffbase Email supports HVE as an outbound relay option.

This article explains how to prepare HVE in Microsoft 365, what information to share with Staffbase, and which settings to configure for reliable, trusted delivery.

You have the following roles:

• Admin role in Exchange Admin Center
• Admin role in Microsoft Entra ID
• Admin role in the Microsoft 365 Defender portal
• Access to the DNS records for your sending domain

Set up High Volume Email in Microsoft 365 for your tenant by following Microsoft’s official documentation. As part of that setup, create a dedicated HVE account in Exchange Admin Center and note the following details, since Staffbase needs them to configure the relay:

• The primary SMTP address of the HVE account, for example hve@yourcompany.com
• An OAuth2 access token for the account, generated using the client credentials flow

For more information, see Microsoft’s documentation on managing High Volume Email for Microsoft 365.

Send the following information to Staffbase Support so the relay can be configured on the Staffbase side:

Item	What to Provide
OAuth2 user	The primary SMTP address of the HVE account
OAuth2 access token (or password)	A valid access token from the client credentials flow, or the account password if using Basic Authentication

You don’t need to provide SMTP host, port, or TLS settings. Staffbase configures these automatically for HVE connections.

Allowlisting Staffbase’s outbound IP addresses in Exchange Online Protection prevents mail from being rate-limited or quarantined at the connection layer.

1. In the Microsoft 365 Defender portal, navigate to Email & Collaboration > Policies & Rules > Threat Policies > Anti-spam.
2. Open the Connection filter policy (Default).
3. Under IP Allow List, add the Staffbase outbound IP ranges for SMTP.
4. Click Save.

1. In Exchange Admin Center, navigate to Mail Flow > Rules.
2. Create a new rule and name it. For example, Bypass Spam Filtering for Staffbase HVE.
3. Set the condition to sender address matches the HVE account address.
4. Set the action to set the spam confidence level (SCL) to -1 (bypass spam filtering).
5. Save and activate the rule.

HVE accounts authenticate from Staffbase’s infrastructure, which may use IP addresses and locations outside your usual approved ranges. Review your conditional access policies so they don’t block the account.

1. In Microsoft Entra ID, navigate to Security > Conditional Access.

2. Review each enabled policy for conditions that could block the HVE account, particularly policies that block sign-ins from non-approved locations or countries, require , or block legacy or basic authentication.

3. Add the HVE account to the exclusions of any policy that applies.

   HVE accounts can’t complete interactive MFA, so any policy requiring MFA must exclude this account.

• Allowlist Staffbase platform and Allowlist Employee Email
• Microsoft documentation on managing High Volume Email.
• For high-volume sending to external recipients, see Microsoft’s documentation on Azure Communication Services Email.