Is it possible to send an encrypted email to a person who you have had no correspondence or contact with beforehand, so that only that person will be able to decrypt and read the message?

Basically, if a business has a new client and they want to send the client an encrypted email, is it possible? Or does the client need to set something up first of all?

I am looking at this from two possible points of view:
1. Sending from an email client - e.g Outlook or Outlook Express.
2. Sending the email from a web site.

I have a client who has the following requirement:
"Security of e-mails and other documents.... the truth is that all of my e-mails sent and received need to be secure as they will often carry personal data."

What would you tell them? Thanks.

You can do that via a digital ID from verisign - costs about $9 and plugs into outlook, if they have a digital id then you can install keys on each others machines and send email in true 128bit encryption.

We had one on all the support email addresses at one stage (dunno if anyone ever renewed them) - a draw back to digital id's were that they only worked in outlook (possibly eudora and netscape), but in some cases caused the other users machine to totally freeze up to 5 minutes before then displaying the email (this was back in 2000 btw- so they could have worked that bug out).

Not sure about a website - would be pretty complex.

You could look at Pgp, although it's rather complicated to use unless you know what you are doing with it.

You could send PGP encrypted emails from a website (if PGP is installed properly on the server), although it's likely you'll be needing a fair amount of control over the server (would you really want your own private keys to be in the hands of your host?).