If you block a sender, and then send them an email, that would put them in your address book (unless you'd unchecked that box) - but would the sender still be blocked from sending you email?

That's just me being curious in case it ever comes up.

And I take it the rule still is that you can't catch anything nasty from an email, it's just the attachments you have to watch out for? (And of course, opening innocuous looking links could mean that you find yourself with a hard disk containing material which is illegal to have there, as well as nasty - but your computer can't get a virus that way. At least that's what I understand to be the case.)