More details will sure help us.
I can't suggest you a provider since I don't have all the details from you but at this moment I will say that you can solve the problem by using proxy, a high anonymous or a socks proxy will do the trick.
While most of the proxy providers don't bother you with spam complains, a proxy will also hide your VPS (i'm assuming you have a problem with the VPS where you host the seo tools). Using more proxy can keep you under the spam radar.
More than that since you are talking about link building try to keep a record of the complain and then remove the domins/IP's from where list when you start to blast.