If being formal, he/she is referred to as doctor.
Dr. and Mrs. or Dr. and Mr.
The proper salutation for a psychologist is "Dr." if they hold a doctoral degree (PhD or PsyD) or "Mr." or "Ms." if they do not have a doctoral degree. It is always best to refer to them based on their level of education and preference.
EdD indicates a doctorate degree. Proper salutaion would be "Dear Doctor xxxxx:"
When using Dr xxxx, the PHD may or may not be used in speaking, in a situation where medical doctors and PHD's would make it unclear the PHD should be used the first time. In written form the Phd is proper when the Dr is used. Mrs does not normally have the Phd appended.
What is the proper salutation for a register of wills, e.g. Honorable John White?
The proper salutation for a probate judge is "The Honorable [Judge's Full Name]."
The proper salutation when writing to a judge is "Dear Judge [Last Name]" or "Your Honor."
the correct salutation for two men is Messrs
Hello.
Your Honor
Dean actually is the proper salutation. One could say: Dean Redmond, would you please sign this form? Alternatively you could just use the Dr. salutation or the Professor salutation if those are appropriate, which they generally are.
The proper salutation for a doctor is doctor or professor depending on their title. In writing the short form can be used which will be Dr. or Prof.