One of the problems that can arise as a result of linking to other websites is if the website you are linking to is banned or penalized by Google. If this happens then Google may actually penalize your own website for being associated with this website and providing a link to it, which could mean your own rankings suffer simply because you are linking to a banned website.
The Site Banned Checking Tool will crawl your entire website and check all your outgoing links do not point to any banned websites to ensure you don't inadvertently jeopardize your own rankings.
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