The poster didn't provide the link it is a feature of the board, if a post contains the words that relate to an article on the site the board creates the link automatically, like for the word booktype.
It sounds like you may have an e-mail service where they have de-activated the links. Is it just text like the rest of the e-mail or is the text of the link different? Have you tried to copy and paste the link into the browser address bar? THis usually works for me when a link won't work as instructed in the e-mail.