Special education teachers, or anyone who calls IEP meetings at your school, can use this letter as a way to contact parents/guardians. In addition, it can be used a way to document attempts and offers made to reach the parents in order to set up the IEP meeting.
One suggestion I have is to use carbon paper or duplicate/triplicate paper with this letter. This helps to retain documentation of contact attempts.
You may also consider reducing the print size of this letter to copy onto your school's official letterhead paper.