Outlook Mailbox – Shared vs Alias

There are several types of email addresses in Microsoft 365. Email this article is only to discuss Shared Email addresses and Alias Email addresses.

A full email mailbox account has an email address with a password to login. Delegated access can be used from this account to access other accounts. This is also known as your Microsoft EntraID (formerly AzureAD) for other uses.

An email alias is an additional address assigned to a full email mailbox. This is commonly used when a user has a last name change. Users want to update their email address to reflect their new name, but still have their old email address for continuity. All emails to both addresses arrive in the same inbox, but only the primary email address has a password used for login.

A shared email address is a single email address to a separate mailbox without a password. Access to this mailbox is delegated to one or more people in your organization. Long term uses include generic email addresses like sales@ or info@.
Short term uses are former full email accounts converted to a shared account. This is done to maintain an email address after a person has left the company. These accounts should be monitored for continued communications for a period of time and then removed. We recommend you setup an automatic reply message to let people know this mailbox will be discontinued. No aliases, only a single address per shared mailbox can be set.