Welcome to Microsoft Community Forums.
Based on the description, it appears that you are facing issues with opening URL's in Yahoo mail using Mail app. I will be happy to help you with this issue.
1) Is the issue confined with a specific URL or with other URL's as well?
2) Do you receive any error message when trying to open the URL's?
3) Do you have any issues in opening the same URL's using Web browser?
4) Have you made any changes on the computer prior to this issue?
Method 1: I would suggest you try opening the links or URL's in the web browser and check if it helps.
Method 2: I would suggest you to copy and paste the URL in the web browser and check if the issue persists.
I hope it helps. If you have any issues regarding Windows in future please let us know. We will be happy to help you.
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