Seems that Mailscanner marks perfectly safe links as dangerous. Adding warning messages to emails and therefore, make you look unprofessional, or make you believe things that are not realy so. Furthermore, look at their website: there is no way of contacting them, or it is hidden behind many procedures. There is noone to take responsability. No contact no address. This alone would make me suspicious. To my opinion: this is very unrelyable and I would not ever use this crap.