Hi,
Thank you for posting in Microsoft Community.
Based on your description, it looks like you're having issue sending emails using your Outlook account. This error message usually indicates that the email address you're trying to send to is invalid or no longer exists. Let's work on this issue together.
To better understand the situation, I would like to ask some questions, such as:
- What email domain are you using? ex. Hotmail.com, Live.com, Outlook.com, etc.
- Are you accessing your email account using Outlook application or Outlook.com in the web?
- Is this error happening on one specific recipient or general? please confirm
- When did this issue started?
While waiting for your response, kindly try the methods below
- Double-check the email address you're trying to send to and make sure it's correct.
- Try sending the email to a different email address to see if the issue persists.
- Contact the recipient and ask them to confirm their email address.
- If the issue persists, delete the contact then readd it on your account
- try deleting the address from the autocomplete list (select it using the arrow keys when it comes up then press Del). Next time you send to the address, type it in or select it from contacts.
I hope this helps! Let me know if you have any further questions or concerns.
Sincerely,
Leonardo_Y