DISPLAY NAME

Question

In Outlook / Microsoft 365, we observe that recipient names are displayed in an abbreviated or formatted manner, for example: “To: Last, First name”, instead of showing the full email address (e.g. [Moderator note: personal info removed]@company.com).

We understand that this may be related to the user Display Name configuration, but we would like to clarify the exact mechanism.

Could you please confirm:

1. Whether the displayed name in the To / From field is always derived directly from the Microsoft 365 / Exchange Display Name, rather than the email address.
2. How Outlook determines the name format (e.g. Last Name, First Name) and whether this is enforced by Exchange or Azure AD.
3. Whether there is any official Microsoft documentation explaining this display behavior.
4. Whether this behavior is configurable by end users, or only manageable by Microsoft 365 / Exchange administrators.

Answer 1

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Hi Chen, Lina-LN 

Based on my research and testing, I am glad to share the insights I have gathered so far regarding your inquiry. 

In Outlook, the display name shown in the From and To fields is taken from the Offline Address Book, which is used as the default source when resolving proxy email addresses. From testing results, Outlook consistently uses the display name listed in the Offline Address Book when populating the To field during email composition. This display name format may differ from the standard First Name Last Name format. 

For reference, you may review: Force Outlook to use the Global Address List to resolve proxy addresses and custom properties in Ca… 

 

The Offline Address Book is generated from the Global Address List and Address Lists. These are controlled at the tenant configuration level and are not configurable from the user client side. 

For additional details, you may also refer to: Address lists in Exchange Online | Microsoft Learn 

From the user perspective, there is an optional workaround. A user can create a personal contact with a display name or full name that differs from the Offline Address Book. When sending an email, the user can:  

Click To > open the Address Book > select Contacts > choose the intended recipient > send the email.  

In this case, the display name shown in the To field on the sender’s Outlook may differ from what is defined in the Offline Address Book. 

I hope this provides helpful context and additional insight. If you have any updates after reviewing this information, please feel free to share. 

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Answer 2

1. In Outlook, the value shown in the To / From fields comes from the message’s RFC 5322 From header, whose format is: From: "Display Name" <EmailAddress> The Display Name portion is what Outlook shows as the friendly name; the email address is shown separately (for example on hover or in the message header). This display name is typically populated from the sender’s directory object (Exchange / Microsoft 365 recipient), not from the SMTP address itself. The email address is the <EmailAddress> part.
2. The name format (for example, Last Name, First Name) is determined by how the Display Name is stored on the recipient object in Exchange / Microsoft 365 / Microsoft Entra ID. Outlook reads and displays that string; the formatting is not derived from the SMTP address but from the directory’s display name value. The recommended header format is: From: "Display Name" <EmailAddress> where Display Name is an arbitrary phrase describing the owner of the address. Microsoft recommends enclosing the display name in quotes and separating it from the address with a space, but the actual text (including Last, First or suffixes like -LN) comes from the directory configuration.
3. Microsoft documents the underlying mechanism in terms of email standards and the From header:
   • The From address (also known as 5322.From) is the sender’s email address in the From header and is what clients display.
   • The header format is defined as From: "Display Name" <EmailAddress> with guidance on how the display name and address should be formatted.
   This explains why Outlook shows a display name rather than the raw SMTP address.
4. For classic Outlook for Windows:
   • For accounts that are not Microsoft Exchange (for example, POP/IMAP), end users can change the name shown to recipients by editing the Your name field in Account Settings. This directly affects the display name that appears in the From header for messages sent from that profile.
   • For Microsoft Exchange accounts, the display name is controlled by the Exchange / Microsoft 365 directory. End users cannot change it in Outlook; only Exchange / Microsoft 365 administrators can modify the display name on the mailbox or user object. The documentation explicitly states that if the account type is Microsoft Exchange, only the Exchange administrator can make this change.

So in a Microsoft 365 business environment using Exchange mailboxes, the abbreviated or formatted names such as Chen, Lina‑LN are coming from the directory’s display name configuration, and changes must be made by Microsoft 365 / Exchange administrators, not by end users in Outlook.

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References:

• Change the display name that email recipients see in classic Outlook
• How Microsoft 365 validates the From address to prevent phishing