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Hi there, I think what William is saying is that site B will receive the benefit of a new linking domain, but that linking domain (site A) is many times stronger than site B because of its extra backlinks. As a result, site B still gains a good amount from receiving the redirect. There are different opinions on this, i.e. on whether a redirect seems to help a lot more than this, and every case in which this takes place seems to have different results, largely because of all the other metrics affecting both sites. It's obviously hard to test this in a controlled environment. There is debate around how much of a boost a cross-domain redirect actually has on the destination website - certainly in days gone by, the site at which the redirect is pointed will receive the vast majority, if not all, of the redirected site's rankings. This can still happen if all of the content on site A's redirected pages is reflected on site B, or if site B's content is sufficiently the same. However, if you were just redirecting for the purpose of making site B stronger and there was no real cross-over between the content of either page / site, this process shouldn't have a hugely beneficial effect on site B.