How would I go about addressing this person?

[mothra]

if he's a professional why not just look him up and see what he puts on the door?

[MrSkippyJ]

or just address him as Dr. so and so and if he doesn't want to be called that he will let you know.

[hispls]

A title replaces a first name. So if Joe Smith is a doctor, he would correctly be "Doctor Smith". This also goes with military and police. Their rank or title is their first name, so they would be Corporal Smith, Lieutenant Smith, etc. People who EARN titles or ranks typically appreciate being addressed as that formally, IMO it's polite to give credit where due. Even if a doctorate is in math or something I assure you that person paid a shitload of money and worked their arse off for it.

[Jessica]

refer to them as Grand Pu-bah.

[Souldrop]

All Dr. refers to is someone who has obtained a doctoral degree. What does it hurt to try and give them credit for their accomplishments? It's better to be more formal than less especially when developing a new contact. Once you meet him in person he may ask you to call him something different, but for now play it safe. I know when I get my doctorate I won't really care, but at the same time I know some people are sticklers about being called Dr. so and so (not many but a few). I would go with Dr. "Last name" first.

[MrSkippyJ]

All Dr. refers to is someone who has obtained a doctoral degree. What does it hurt to try and give them credit for their accomplishments? It's better to be more formal than less especially when developing a new contact. Once you meet him in person he may ask you to call him something different, but for now play it safe. I know when I get my doctorate I won't really care, but at the same time I know some people are sticklers about being called Dr. so and so (not many but a few). I would go with Dr. "Last name" first.

i bet you will change your mind pretty quickly once you earn that title. Especially in professional settings.

[Ahmed Johnson]

The thought of Dr. n8 banning dumbasses got me cracking up.

[Souldrop]

In a professional setting it goes without saying that unless people are on a first name basis that Dr. is the default title, but for students it's not like I would ream them a new one if they called me Mr. Now given the fact the OP knows the guy has a doctorate and is asking him for a favor then he should address him as such until told otherwise. The contact may turn into a valuable asset of gaining experience in the field and a LOR if he is able to go further than shadowing.

[Guest]

I've had professors who clearly state in their syllabus that it is inappropriate

to address them as "Dr." because that name title is designated for those in the medical field, not educational doctorates.

You should be fine.

It isn't designated for the medical field though. You had some weird professors.

No argument there, they were mostly acid-flashback english teachers

I clearly remember one kid getting bitched out for calling a teacher "Doctor Alscher" (Alshcer being his last name)

Although his name was written Dr. Peter Alscher.

[n8ball2013]

The thought of Dr. n8 banning dumbasses got me cracking up.

Ive considered continuing school to that level but its worthless in my field.