You may sometimes serve the SUMMONS and VERIFIED PETITION FOR DIVORCE outside of the United States using a commercial courier service which requires a signature for delivery. However, you must be certain that this method of service is allowed in the country where you are serving. In addition, your judge may want you to use the other service methods approved for that country. This is especially true if the country allows service pursuant to the Hague Convention on the Service Abroad of Judicial and Extrajudicial Documents. You absolutely must comply with the requirements of the Hague Convention or your service may not be valid, which means your divorce won't be valid. In most instances, such as service in Mexico, which is a Hague Convention country, service by a private courier instead of providing the Central Authority with the USM 94 form, would not be proper.
If you haven't done so already, you should research the methods of service approved for the country where you are serving by visiting the following website:
http://travel.state.gov/law/judicial/judicial_680.html.
As of May 1, 2012, the U.S. State Department web site shows that service by courier (mail) is not permitted in:
Argentina
Bulgaria
China, PRC
Czech Republic
Egypt
Germany
Greece
Hungary
Japan
Korea
Kuwait
Lithuania
Norway
Poland
Russian Federation
San Marino
Slovak Republic
Sri Lanka
Switzerland
Turkey
Ukraine
Venezuela
It is your responsibility to ascertain whether or not service by courier is appropriate in the country you are serving in. If service by courier is not permitted, service by publication might be possible. It's your responsibility to research the law to figure this out. Some countries still require service by letter rogatory. Once again, it is your responsibility to do the research to figure this out.
There are special requirements for service in some countries such as Mexico. The State Department's web site contains information concerning most countries, such as service in Mexico at:
http://travel.state.gov/law/judicial/judicial_677.html
To research any country go to The State Department's web site at http://travel.state.gov and in the search box type in service of process and the name of the country, for example "service of process japan".