.mail.onmicrosoft.com

.mail.onmicrosoft.com is a domain name used by Microsoft for its Office 365 email services. When you sign up for Office 365, you can choose a custom domain name for your organization's email address, but if you don't specify one, Microsoft will automatically assign a default domain name in the format .onmicrosoft.com.

For example, if you sign up for Office 365 and don't specify a custom domain name, your email address might look like this:

[email protected]

This domain name is used to route email traffic to your Office 365 mailbox. It's a unique identifier for your organization's email service and is used to authenticate your email account.

Here are some key things to know about .mail.onmicrosoft.com:

1. Default domain: .mail.onmicrosoft.com is the default domain name assigned to Office 365 accounts that don't specify a custom domain name.
2. Unique identifier: Each Office 365 organization has a unique .onmicrosoft.com domain name that identifies its email service.
3. Email routing: Email traffic is routed to your Office 365 mailbox using this domain name.
4. Authentication: The .onmicrosoft.com domain name is used to authenticate your email account and ensure that only authorized users can access your mailbox.
5. Custom domain: If you want to use a custom domain name for your organization's email address, you can specify one when you sign up for Office 365 or later. This allows you to use a domain name that's more specific to your organization, such as example.com.

Overall, .mail.onmicrosoft.com is an important part of the Office 365 email service, and it helps to ensure that your email account is secure and easily accessible.