How to send from Alias in Office 365 (App/Web) (Not Shared Mailbox)

When you use an alias to send an email it will be preserved in the From and Reply to field for the recipient. The recipient will see only your alias and not your primary email address.

Enable Send Email from Alias for the tenant

The send from alias option is turned off by default, so if you want to use this feature you will need to enable it in the Exchange Online Admin center or with PowerShell.

Tip: Allow a few minutes for the changes to update before sending from the alias, otherwise the recipient will still see the principal email address when sending an email.

Open the Exchange Admin Center

1. Click Settings 
2. Click Mail flow
3. Enable Turn on sending from aliases

Sending Email From Alias in Outlook App

Sending an email from an Alias is similar to sending an email from a Shared Mailbox  

1. Choose New Mail
2. Click on the dropdown next to 'From'
3. If you don't see the From field at the top of your message, choose Options > From.
4. Once you click on From, you will have multiple options to choose from, Choose the Alias email address.
5. In case you don't see your shared email address, choose Other email address and then type in the alias email address. this will be done one time. Next time the alias will be listed in the From field

Sending Email From Alias in Outlook Web

To send mail from your alias address in Outlook web is pretty simple. Make sure that the From field is displayed (otherwise enable it under options).

• Select From
• Choose Another email address
• Type your alias and click Ok

The next time you can just select the alias from the dropdown menu in the From field.