There is a number of providers available for sending letter and packages, the largest in Germany being the ‘Deutsche Post’ (German Post Office).
Stamps can be bought either at the counter in Deutsche Post branches or sometimes from a machine (as of July 2014).
Post cards: € 0.45 (national)
Post cards: € 0.75 (international)
Normal letters: € 0.60 (national)
Normal letters: € 0.75 (international)
Heavier letters and packages should be weighed and stamped correspondingly directly at the post office to avoid being returned to the sender.
If you are expecting a package but are not at home when it is delivered, the package will either be left with a neighbour of brought to the appropriate branch of the post office. You will be informed about where you can retrieve your package via a notice in your letterbox.