Anytime you put your e-mail address on a web site, you make it available for anyone to visually read it with the naked eye. Of course, that's why you would put it on a web page in the first place!
The real danger of having one's e-mail address on a web site is the software that spammers use for making their lists of addresses to send spam to. Basically, their software visits web pages and scans and records any e-mail addresses it finds.
However, if you are using an updated version of Joomla 1.5 you can put your e-mail address in an article and not worry about your address being "farmed" in the manner described above. This is due to a trick that Joomla does to hide e-mail addresses in the code that spammer-scanners look at.
var prefix = 'ma' + 'il' + 'to';
var path = 'hr' + 'ef' + '=';
var addy92644 = 'tim' + '@';
addy92644 = addy92644 + 'cybersalt' + '.' + 'org';
document.write( '<a ' + path + '\'' + prefix + ':' + addy92644 + '\'>' );
document.write( addy92644 );
document.write( '<\/a>' );
document.write( '<span style=\'display: none;\'>' );
</script>This e-mail address is being protected from spambots.
document.write( '</' );
document.write( 'span>' );
The above cuts the spammer's scan short and let's real people see your address. A real person might send you stuff you don't want, but a spammer can't be bothered to read every web page visually.
There is one caveat to mention in all of this. If you put your e-mail address in some other parts of Joomla (let's say a module or some component like the FAQ component I am useing to anwer this question) your address can appear on a scan. So it's still good to use Joomla's contact form for letting new people get in touch with you. They won't see what your address is until you reply to them from your e-mail program.