When you try to send an email from an alias address in Outlook, the alias may not appear in the From field dropdown list. This happens because Outlook only shows addresses that are explicitly added to your profile as SMTP aliases with send-as permissions. This article explains why the alias is missing and provides step-by-step instructions to add it using Exchange admin tools or local Outlook settings.
Key Takeaways: Adding SMTP Aliases to Outlook’s From Field
- Exchange Admin Center > Recipients > Mailboxes > mailbox > Email Addresses: Add the alias as an SMTP address and set it as a secondary address.
- Exchange Admin Center > Recipients > Mailboxes > mailbox > Mailbox Delegation: Grant Send As permission to the user for the alias address.
- Outlook > File > Account Settings > Change > More Settings > Internet Email: Manually add the alias as an email address in the user’s profile for non-Exchange accounts.
Why Outlook Does Not Show Your SMTP Alias in the From Field
Outlook retrieves the list of addresses in the From field from two sources: the Exchange mailbox configuration and the local Outlook profile. An SMTP alias that is correctly assigned to your mailbox in Exchange will appear in the From field only if two conditions are met. First, the alias must be added as a secondary SMTP address on your mailbox. Second, you must have Send As permission for that address. Without Send As permission, Outlook hides the alias from the dropdown list. For non-Exchange accounts such as IMAP or POP3, the alias must be manually added to the Outlook profile settings. This article focuses on the Exchange scenario because it is the most common cause of the missing alias problem.
Steps to Add an SMTP Alias to Outlook’s From Field
The fix requires two actions in the Exchange Admin Center: add the alias as a secondary SMTP address, then grant Send As permission. If you use a non-Exchange account, follow the manual profile method instead.
Method 1: Add SMTP Alias via Exchange Admin Center
- Open the Exchange Admin Center
Sign in to the Microsoft 365 admin center at admin.microsoft.com. Go to Admin centers > Exchange. This opens the Exchange Admin Center (EAC) in a new browser tab. - Navigate to the recipient mailbox
In the EAC left menu, select Recipients > Mailboxes. Find the user mailbox that needs the alias. Click the mailbox name to open its properties. - Add the SMTP alias
In the mailbox properties window, select the Email Addresses tab. Click the plus icon and choose SMTP. Enter the alias email address, for example, alias@domain.com. Ensure the address type is set to SMTP and the format is correct. Click OK to save. The alias now appears in the list of email addresses. Click Save at the bottom of the properties window. - Grant Send As permission
In the same mailbox properties window, select the Mailbox Delegation tab. Under Send As, click the plus icon. Search for the user who will send from the alias. Select the user and click OK. Click Save. This grants the user permission to send email using the alias address. - Wait for replication and restart Outlook
Exchange changes take up to 30 minutes to replicate across all servers. Close and restart Outlook. Open a new email, click the From button, and verify the alias appears in the list.
Method 2: Manually Add Alias in Outlook Profile for Non-Exchange Accounts
- Open Outlook Account Settings
In Outlook, go to File > Account Settings > Account Settings. Select your email account and click Change. - Access More Settings
In the Change Account window, click More Settings. Select the Internet Email tab. - Add alias to the user name or email address fields
In the User Information section, replace the Email Address field with the alias address. Alternatively, in the Logon Information section, enter the alias in the User Name field if your provider supports it. Click OK and then Next. Outlook will test the connection. If the alias works, the From field will show it.
Common Issues After Adding an SMTP Alias
Alias Still Does Not Appear in the From Field
If the alias does not appear after following Method 1, verify that the Send As permission was applied correctly. Open the mailbox properties in EAC and confirm the user is listed under Mailbox Delegation > Send As. Also check that the alias is marked as a secondary address, not the primary reply address. The primary address is the default From address. Secondary addresses appear in the dropdown only if Send As permission is granted.
Outlook Shows the Alias but Cannot Send
When the alias appears but sending fails with a permission error, the Send As permission may not have propagated. Wait 30 minutes and try again. If the error persists, remove the user from the Send As list, save, add the user again, and save. This resets the permission.
Alias Works in Outlook for Windows but Not in Outlook on the Web
Outlook on the web uses a different permission model. To send from an alias in OWA, the alias must be added to the user’s mailbox as an SMTP address. The Send As permission is not required for OWA because OWA uses the primary mailbox identity. If the alias is missing in OWA, add it as a secondary SMTP address in EAC and refresh the OWA session.
Exchange Admin Center Does Not Show the Mailbox Delegation Tab
The Mailbox Delegation tab appears only for user mailboxes that are not shared or resource mailboxes. If you are using a shared mailbox, assign Send As permission using the Exchange Management Shell. Run the command: Add-MailboxPermission -Identity “sharedmailbox@domain.com” -User “user@domain.com” -AccessRights SendAs.
Exchange Admin Center vs Outlook Profile: Key Differences for Adding Aliases
| Item | Exchange Admin Center Method | Outlook Profile Method |
|---|---|---|
| Account type supported | Exchange Online, Exchange Server | IMAP, POP3, Exchange if profile is manually configured |
| Permission required | Admin access to Exchange Admin Center | User-level access to Outlook account settings |
| Alias visibility | Appears in From dropdown after replication | Appears immediately after profile change |
| Send As permission handling | Granted separately via Mailbox Delegation | Not required; alias is part of account credentials |
| Replication delay | Up to 30 minutes | None |
After adding the SMTP alias and granting Send As permission, restart Outlook to refresh the address list. Check the From field in a new email to confirm the alias appears. If the alias still does not show, verify the alias format and that the user has Send As permission at the mailbox level. For persistent issues, use the Exchange Management Shell to inspect mailbox permissions with the command Get-MailboxPermission -Identity “user@domain.com”. This command lists all users who have Send As permission for that mailbox.