Hello, and welcome to Mail Flow Scenarios in Microsoft 365. In this lesson, we'll take a quick look at the different ways mail flow can be set up in Microsoft 365. Microsoft 365 offers several ways to configure how email gets delivered to user mailboxes. While many organizations want Microsoft 365 to manage all mailboxes and filtering, there are others that have more complex mail flow requirements for specific business needs. For example, most organizations will deploy Microsoft 365, so that they can manage all of their mailboxes and mail flow using Microsoft 365. This scenario often applies to new Microsoft 365 customers that host all of their mailboxes in Microsoft 365. It's also often leveraged by organizations that have an existing email service, but plan to quickly move all of their mailboxes to Microsoft 365 at once. In this case, inbound email from the Internet flows directly to exchange online. Some organizations prefer to manage their mail flow using a third-party cloud service along with Microsoft 365.

For example, an organization in this situation may plan to host all mailboxes in Microsoft 365, but instead of using the built-in spam filtering and whatnot, the organization might prefer to use its own third-party anti-spam solution. Think Mimecast or Proofpoint. In these cases, email from the Internet first hits the third-party spam filter, which then sends the mail onto exchange online. Organizations will also often use other third-party services like archiving or auditing services as well. In these cases, mail flow must be configured to send all email from the Internet to the third-party solution for archiving or auditing. In each of these scenarios, mail flow configuration is a little more complex. Organizations with mailboxes in both Microsoft 365 and on-prem will have their own mail flow challenges to address. For example, if an org, like the Blue Widget Corporation is migrating its mailboxes to Microsoft 365, it may have a need for keeping some mailboxes hosted on the on-prem exchange server, even though it wants to leverage Microsoft 365 for spam filtering.

In this scenario, you have messages being sent from the on-prem server to the Internet via Microsoft 365. Meaning that Microsoft 365 would ultimately be sending and receiving all messages. This is actually a pretty complex mail flow configuration. Another scenario where an organization with mailboxes in both Microsoft 365 and on-prem needs to configure specific mail flow, would be a case where the org is migrating its mailboxes to Microsoft 365, but wants to keep some mailboxes on-prem while leveraging the existing on-prem filtering and compliance solutions that are already in place. In this scenario, all messages coming from the Internet to the cloud mailboxes have to be routed through the on-prem server. Messages sent to the Internet from the cloud mailboxes also need to be routed through the on-prem server. This is another fairly complex mail flow setup.

And yet another complex mail flow scenario that involves mailboxes on-prem and in the cloud, you may have an organization that's migrating its mailboxes to Microsoft 365, but once to not only keep some mailboxes on-prem, but it might also prefer to use an existing on-prem filtering or compliant solution that's already in place. In this type of mail flow scenario, all messages sent from the Internet to the cloud mailboxes would have to be routed through the on-prem server as would messages being sent to the Internet from cloud mailboxes. In this situation, the email domain's MX record would need to point to the on-prem server. Again, this is another complex setup. And of course, you have the same scenario where an org is migrating its mailboxes to Microsoft 365, wants to keep some mailboxes on-prem and wants to use an existing on-prem filtering and compliance solution. But in this case, the org wants all messages sent from the on-prem servers to relay through Microsoft 365 to the Internet.

This is another very complex setup that requires the domain's Mx record be pointed at the on-prem server. Organizations will also sometimes need to manage mail flow using a third-party cloud service with mailboxes on Microsoft 365 and on-prem. In these kinds of cases, the organization is often migrating mailboxes to Microsoft 365 while wanting to keep some mailboxes on the on-prem exchange server. At the same time, the org wants to use a third-party cloud service to filter spam from the Internet. In these situations, the org will want to route emails bound for the Internet through Microsoft 365 in order to protect the on-prem server's IP addresses from being added to external block lists. As you might have guessed, this is one of the most complex mail flow configurations. And then the last mail flow scenario you'll want to familiarize yourself with is that in which you need to send emails from a printer, or scanner, or even fax app through Microsoft 365. In this type of situation, all mailboxes are often hosted in Microsoft 365.

However, you might have a printer or scanner or facts that needs to send email via Microsoft 365. This isn't a terribly difficult mail flow to set up, but it does require some planning. So, now that you've been introduced to the many different mail flow scenarios that you might encounter, join me in the upcoming lectures where we'll take a look at each one of these in a little more detail.