The stature of the institution in which you earned your degree Integrate that into your pitch. The reputation of your collaborators Incorporate that into your pitch. Now you are ready to make contact with your key gatekeeper. Each has its benefits and drawbacks. Snail mail is formal.
Email is less formal.
Both have the added advantage of allowing you to carefully delineate your pitch, without any interruption. You avoid the secretary. Email makes it easier for the gatekeeper to contact you. Of course, not everyone appreciates the informality of email. You may want to call the gatekeeper.