Outlook Email Sending Issue

I'm experiencing an issue with Outlook where I'm unable to send emails, although I can still receive them. I do not receive any error messages when attempting to send. I have not changed any account settings or passwords recently. However, I can send emails using a different email client.

Requirements:
- Diagnose and fix the issue preventing me from sending emails on Outlook.
- Ensure that my account settings are correctly configured.
- Verify that no other underlying issues are causing this problem.

Ideal skills and experience:
- Proficiency in troubleshooting Outlook email issues.
- Experience with email account configurations and settings.
- Ability to resolve authentication or connectivity problems.
- Good communication skills to explain the solution and ensure everything is working correctly after the fix.