Windows 10: Why is outlook sending me failure to deliver when I send emails to my own address

I send myself a message and I get this post failure message. Delivery has failed to these recipients or groups:robroy_walton@hotmailYour message wasn't delivered because the recipient's mailbox is undergoing maintenance and can't accept messages now. Please try resending the message later.Diagnostic information for administrators:Generating server: BN6PR19MB0116.namprd19.prod.outlook.comrobroy_walton@hotmailRemote server returned '501 5.1.6 Recipient addresses in single label domains not accepted [SJ0PR19MB4446.namprd19.prod.outlook.com 2024-12-26T01:09:58.655Z 08DD249830196F54]'Original messa

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How to enable 'send as' in Outlook (Office 365 email)


Both. In OWA (web app) the users need to select Show from:




When doing this first time, the new allowed Send As email is not shown in the From drop down list. Users need to right click their usual Send As address and select Remove, then add the new Send As address manually:




After that the new address will be shown and can be selected from the drop down list.

In Outlook desktop app users need to manually remove their usual Send As address and add the new one, thereafter the new address will be shown in From drop down list.

 

Windows 10 Outlook will not send emails

Hi Donita,

Failure on sending messages with Outlook can be caused by an incorrect server settings. To isolate your concern, we'd like to ask the following:

• Which Outlook version are you using? You can check this
  link to help you identify.
• Have you tried sending the message to a different email address? If yes, did you encounter the same error?
• Have you made any recent changes on your device prior to your concern?
• What are the troubleshooting steps that you've performed to resolve your concern?

We're looking forward to your response.

 

Difficulty Sending Outlook Emails with Attachments

If you access the email address you use in Outlook 365, through a browser, will it let you send attachments?

Trying to isolate is this an Outlook or an email account issue.