According to Deutsche Post, a domestic mail address in Germany consists at least of
[name]
[street name and number]
[postal code] [place of destination]
For example:
Erich Müller
Goethestr. 13
22767 Hamburg
However, it is customary to add the form of address in the accusative case. (In Switzerland, the form ‘Herr’ is considered permissible.)
Herrn
Erich Müller
Goethestr. 13
22767 Hamburg
(Note that, since 1 September 1999, Deutsche Post prefers that you no longer prefix the numeric postal code with any country code, for example neither “DE-22767 Hamburg” nor “D-22767 Hamburg”.)
For international mail, according to the Universal Postal Union (UPU), the name of the place of destination and the name of the country of destination shall be written in capital letters.
Herrn
Erich Müller
Goethestr. 13
22767 HAMBURG
GERMANY
According to the UPU, the name of the country of destination shall be written preferably in the language of the country of origin. To avoid any difficulty in the countries of transit, it is desirable for the name of the country of destination to be added in English or another internationally known language. (Note that actually French is the official language of the UPU. English was added as a working language in 1994.)
For example, the address of a letter posted in Poland to Germany contains the name of the
destination country in Polish and English (or another internationally known language):
Herrn
Erich Müller
Goethestr. 13
22767 HAMBURG
NIEMCY – GERMANY