Is this a good follow up email after a thank you letter? I had a phone interview for a job 10 days ago...?

No, a follow up letter or email is highly unnecessary. Your qualification or suitability for the position has been essed during the phone interview 10 days ago. If you are selected, they'd call you for a face-to-face interview. Always remember, if you are a suitable candidate, they need you just as bad as you need them.