Each Exchange mailbox can be assigned multiple email addresses. These proxy addresses are also called aliases. Until now, you could use them to receive messages, but to send emails, you had to use the standard address. Now Microsoft 365 also allows you to send email via an alias.

Previously, if you wanted to send an email from an alias address, workarounds such as using a shared mailbox or distribution group were necessary.

Sending messages on behalf of an alias is on Microsoft's roadmap, and it is currently being introduced in Exchange Online. This option is available in both the Outlook desktop client and the web app.

Changing the tenant configuration

To enable sending email from an alias address, you first need to modify the organization's configuration at the tenant level. The following PowerShell command serves this purpose:

Set-OrganizationConfig -SendFromAliasEnabled $true
Changing the organizational configuration with PowerShell

Changing the organizational configuration with PowerShell

Use the following cmdlet to ensure your configuration is successful:

Get-OrganizationConfig | Select-Object SendFromAliasEnabled

Managing alias addresses

Alias addresses can be maintained via several administration options. If you prefer a graphical interface, you can find it in the Microsoft 365 Admin Center or the Exchange Admin Center.

The link to the aliases can be found in the user properties

The link to the aliases can be found in the user properties

There, follow the link Manage username and email in the account properties. On the following page, you can add aliases using the corresponding field.

Adding alias addresses via the Exchange Admin Center

Adding alias addresses via the Exchange Admin Center

In PowerShell, the Set-Mailbox cmdlet is used to manage aliases (the respective parameter is named EmailAdresses). The following command adds additional SMTP addresses:

Set-Mailbox -Identity [Identity] -EmailAddresses @{add="[alias-address]"}
Adding aliases for Exchange Online with PowerShell

Adding aliases for Exchange Online with PowerShell

Sending from the alias address

In my test environment, sending from the additional SMTP address was possible after a few minutes. It might take a bit longer if the change hasn't taken effect yet. For testing, I used a current Outlook version.

There, you first have to open the "From" field and then select Other Email Address. In the dialog box that appears, you can enter the desired sender address.

Sending mail from an alias address in Outlook

Sending mail from an alias address in Outlook

To the recipient, the mail looks as if the alias were the primary SMTP address (as shown in the following figure).

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In the email header the alias address appears as the sender

In the email header the alias address appears as the sender

The alias also appears in the email header as the From address.

3 Comments
  1. Kevin 2 years ago

    I have just followed your instruction

    A parameter cannot be found that matches parameter name 'SendFromAliasEnabled'.
        + CategoryInfo          : InvalidArgument: (:) [Set-OrganizationConfig], ParameterBindingException
        + FullyQualifiedErrorId : NamedParameterNotFound,Set-OrganizationConfig
        + PSComputerName        : outlook.office365.com

    Do you have any advice ?

    • Author

      Hi Kevin,

      do you have a proper connection to EOL with PowerShell? See here

      You need also the permission to change the value.

      Regards

      Benjamin

  2. Victor 2 years ago

    SmartReply 365 (https://www.ivasoft.com/smartreply365.shtml) is an utility for Outlook desktop (Windows) users who have enabled the Microsoft feature to send emails from an alias in Office 365.

    This utility will automatically populate the proper From: address when you reply to or forward a message received as an alias.
    In other words, if you get a message addressed to jdoe_alias@contoso.com and hit Reply(Reply All, Forward) button, the replied/forwarded message will have jdoe_alias@contoso.com in the From: field.
    In addition, SmartReply 365 can assign different signatures to different aliases.

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