Human Resource Department
(Address of employer)
(My home address)
January 20, 2008
Thank you very much for offering me the position of Consultant with ABC.
Unfortunately, I had accepted a position with another company before your offer came in.
I sincerely appreciate you taking the time to interview me and to share information on the job opportunity and your company.
Again, thank you for your consideration.
I would keep it short!
Student or Learner