It has been a bit since I posted. When you are in IT you are involved in a lot of projects apart from day to day work, but here is a good one I came across in my work. Dealing with High Volume Emails through Exchange online.

What Would Use High Volume Emails?

That s a very good question. In an organization you could have an individual who sends a lot of email from their inbox, a device like a scanner or copier that send to recipients through email to LOB Apps that send out email notifications as part of the apps process.

Microsoft has done what they can enabling sending High Volume Email email through Exchange but they have to be careful not to clog up the system. Especially if it gets compromised. They have default limits in place.

Exchange Sending limits

The following limits have been put in place for mailboxes by default. They are:

Recipient Rate Limit: 

This is a rolling 24-hour limit on the total number of recipients a mailbox can send to. 

• A typical limit is 10,000 external recipients per day. 
• This limit includes both internal and external recipients. 
• For trial tenants, the limit is 5,000 external recipients. 

Recipient Limit: 

This is the maximum number of unique recipients an email message can have. 

This limit is often set at 1,000 recipients per message. 

Message Rate Limit: 

This limits the number of emails a single mailbox can send per minute. 

• The default is 30 messages per minute. 
• Emails that exceed this limit are throttled and delayed. 

Why These Limits Exist in High volume Email

• Preventing Bulk and Spam Email: Exchange Online is designed for email and collaboration, not for bulk commercial email campaigns. These limits help prevent abuse and maintain service quality for all users. 
• Protecting Your Organization: The recipient rate limit is a safeguard against compromised accounts from being used to send large volumes of spam and potentially damaging your organization’s reputation. 

What Happens When You Hit a Limit

• If you hit the recipient rate limit, you will receive Non-Delivery Reports (NDRs) for your undelivered messages. 
• You’ll need to wait for the 24-hour period to pass before you can send more messages to that recipient group. 

What can you do to Send High Volume Email?

Microsoft recommends using a specialized third-party provider for legitimate High Volume emails. Examples include Mailchimp or Constant Contact are built for sending high volumes of email and are much more suitable for marketing and bulk communications.

However there is a new service in preview by Microsoft you can try called High Volume Email. It looks to be in its infancy but it has some functionality. Let me lay it out for you.

First, you will need to go the new High Volume Email section in the Exchange Online Admin portal. From their, you will need to add an HVE Account. You can also use PowerShell to add an HVE account. Once you have done that, you can use the following info for you Device or App to send email:

Limitations or High Volume Email

You still may need to go to third party services if the following limitations do not fit your needs:

High Volume email exchange is limited by sender reputation risks, strict rate limits for external recipients (e.g., 2,000 per day per tenant in Exchange Online), restrictions on sending to external domains, and requirements for updated authentication methods and potential application code changes.

So it looks like you have options!

Dan

I am an IT professional with over twenty five years experience in the field. I have supported thousands of users over the years. The organizations I have worked for range in size from one person to hundreds of people. I have performed support from Help Desk, Network / Cloud Administration, Network Support, Application Support, Implementation and Security.