Respected Sir/Madam,
I am writing this email to inform you that my name is _______ (name) and I am working as a ________ (designation) having employee ID _______ (mention ID). I would like to bring to your attention that I have an ____________ (doctor/any other) appointment during the work hours. As it is an emergency situation, so I need ____ (hours) time off for the same.
I hope that you will consider this a genuine request and grant me permission for the same. If you need to contact me, you can always feel free to contact me at _______ (contact number).
Thank you for your time and consideration.
Yours sincerely,
__________ (Name),
__________ (Contact details)