The Deutsche Post office is surprisingly good at forwarding mail if you are planning to be away from home for an extended period of time. We have had it forwarded around Europe and even to Japan and Canada. And amazing it has worked! Costs €20 for up to six months or €25 for 12 months and you can set up several addresses if you’ll be moving around. You can fill out a form online and they even called my husband to clarify the addresses.
mybielefeld 