A user who has two or three (or a dozen) SMTP aliases associated with his name wants to actually send an email and have it appear to be from one of those aliases! I bet you tested and confirmed that he could receive email to those aliases, but now you are stuck trying to figure out why he cannot send as one. The bad news is that this is by design. The good news is, we can make it work with just a little effort.
This is going to require work on the client side, specifically in Outlook. We are going to set up a kind of shadow account in Outlook to use the SMTP alias. No, sorry, no PowerShell or global way in the portal to make this work.
- Log onto the O365 portal https://mail.office365.com and go to your webmail.
- Click the Options link and choose See All Options.
- Choose My Account, and click the link for ‘Settings for POP, IMAP, and SMTP access’.
- Copy the server FQDNs for POP and SMTP. They will probably be the same, but make sure.
- In Outlook, click File, then Account Settings, and then Account Settings again.
- On the E-mail tab, click New.
- Click ‘Manually configure server settings or additional server types’, and then click Next.
- Select Internet E-mail, and then click Next.
- Configure the Internet account with the appropriate information
Your name: Your display name.
E-mail Address: The alias that you want to send from.
Account Type: POP3
Incoming mail server: Use the POP server that you found in step 4, something like pod#####.outlook.com.
Outgoing mail server (SMTP): Use the SMTP server that you found in step 4.
Username: Use your UPN
Password: This will be something like ********
- Now click More Settings, click the Outgoing Server tab, and click to select the ‘My outgoing server (SMTP) requires authentication’ check box.
- Click the Advanced tab, and then click This server requires an encrypted connection (SSL).
- In the Outgoing server (SMTP) box, type 587.
- In the ‘Use the following type of encrypted connection’ list, click TLS.
- Click Ok.
- Click Next, test the account settings, and then click through to Finish.
- Click File, Options, Advanced.
- Scroll down to Send and receive and click the Send/Receive button.
- In the Group Name area, select All Accounts, and then click Edit.
- In the Accounts list, select your new email alias account.
- Click to deselect the ‘Include the selected account in this group.’
- Click OK, click Close, and then click OK.
- Create a new email message, click the Options tab, find the Show Fields group, and click to show the ‘From: field.’
- Send a test message.
If all goes well, you should now be able to send email using that alias, and most recipients will be none the wiser.