For the developed countries, deliverability is greatly enhanced when meeting requirements for automation compatibility. Make sure postcodes are included and placed in the proper position in the address. Don't forget to list the country in the last line of the address. Foreign names can often be confusing as to proper use and gender. When in doubt, it may be best to avoid personalization.
Standard valedictions can also vary from country to country.
You may come across as being too personal or too formal depending on your audience. As always, research and care in planning will help you avoid appearing unsophisticated in your approach. If translating, make sure you use a native speaker to avoid any embarrassing gaffs in your copy. If you are mailing a catalog, it is often helpful to have an order form in the local language even if the rest of the catalog is in English. Many companies print the address label in characters of the local language to assist deliverability in the foreign postal administration.