Hi,
thank you very much, especially to Perlbotics for his suggestions on mime::tools, I'm going to play with that library for a while.

I agree that many users will end up ignoring the message, sad but true. We use anti-spam and anti-phishing systems that block most malicious emails, but there is no system that is 100% effective. We carry out regular awareness campaigns, when we detect a phishing email we warn all users who have received it that it is a malicious message, we send fake phishing messages and we force people who are deceived to take a training course... even so, there are users who continue to fall into the trap. I think this is about putting layers that increase security, in this case on the weakest link in the chain, the users. This is another layer, nothing more, it may not be especially effective, but if I can get at least one user not to fall into the trap in each attack, it will have been worth it. When this one is working I'll put another, and then another and another. This is part of my job.

Again, thank you very much, any other suggestions are welcome