From the pilot credentials website:
Candidates for jobs involving handling or access to U.S. mail cannot be considered for employment if they have resided outside the U.S., Guam or Puerto Rico for more than (6) six months during the last (5) years prior to today's date, other than the following verifiable exceptions: active duty in the U.S. Uniformed Service; trailing spouse or dependent of someone working for the U.S. government (military or civilian); missionary; student attending school in a foreign country; Peace Corps participant; employee of a U.S. based employer/company or other extraordinary circumstances.
I think you're OK because you're an "employee of a U.S. based employer." You might want to clarify and for certain have written documentation as you've stated that you're there in V. on a contract with a US based company. Diplomatic relations have nothing to do with FedEx requirements and the requirements set upon FedEx from the US gubmint because we carry US mail.