Using Outlook for iOS for personal email and calendar management
Sorry to hear that you’re having trouble with this situation. Could you please provide a few more details?
Is the account you use to send emails from the Outlook app configured with a Microsoft email address, such as @outlook.com, @hotmail.com, or @live.com, or is it using an email address from a third-party domain?
Also, could you please share a screenshot showing how it looks in the Outlook app when you try to send an email? Please make sure to hide any personal information, email addresses, or other sensitive data. Do you get a non-delivery notification?
Have you already tried removing the account from the Outlook app, restarting the device, and then adding the account again? This can help refresh the account configuration and cached data.