Can I have LinkMachine automatically reject invitations to exchange links with a particular domain or invitations submitted by a particular webmaster?

Yes. You can enter the domain name of a site that you do not wish to accept invitations from, in the Content Filter under Change Settings, Link Approval Settings. Any link submissions for any pages on that domain will then be automatically rejected. Likewise you can enter the e-mail address of a webmaster that you do not wish to accept link exchange invitations from, in the Content Filter.

For more information about the Content Filter, see this page.