USPS claims they will forward your mail, once a week, for $20.
We use mail hold and a friend that weeds out the junk and sends us anything that looks worth sending. After the 30 days of hold he picks it up and then we restart the hold for another 30 days. We have only done this for 60 days so I am not sure if USPS will let us keep doing it for 6 months or so.
We provide him the USPS prepaid envelopes and an address. When he goes on vacation we keep his dog for him so it is free to us except for the envelopes.