The minute that you read this
'As you know, Three-way linking (also known as Triangular linking) plays a very important role in search engine ranking. If you are interested in link exchange and agree to add my link to your website, please use the information provided below.'
Then you should have realised that the guys know nothing about
SEO and dropped it like the good ol' hot potato' - So if it is a 'scam' they are not doing themselves any favours.