Hi guys,

An email software vendor managed by a different area of my company redirected 100 domains used for unsolicited email campaigns to my main domain. These domains are very likely to get blacklisted at some point. My SEO tool now is showing me all those domains as "linking" to my main site as do-follow links. The vendor states that this will not affect my main domain/website in any way. I'm highly concerned. I would appreciate your professional opinion about this. Thanks!!

I doubt blocking countries can have any negative effect on your SEO. Like in your case our company's customers are located only in US. We have blocked many foreign countries for exactly the same reasons you name and never had any negative effects on our SEO work due to the IP blocks. It's more...you may actually see a decrease in your website's bounce rates what is supposed to be good for your ranks.

I doubt blocking countries can have any negative effect on your SEO. Like in your case our company's customers are located only in US. We have blocked many foreign countries for exactly the same reasons you name and never had any negative effects on our SEO work due to the IP blocks. It's more...you may actually see a decrease in your website's bounce rates what is supposed to be good for your ranks.