Setting up email - FQDN

Hi,

I'm trying to set up my email and I was wondering what I should use as the FQDN.

I seems as if I have a choice between:
* myhost.mysite.com

mysite.com</list> 

myhost.mysite.com is the default option when 'Postfix Configuration' asks me for my 'System mail name'. Is it ok for me to use mysite.com instead of the default?

I'm totally new to this, so I get a bit nervous when I choose something different to the default option during installation :lol:

My preference would be to use mysite.com (I already used this when I set my reverse DNS). My guess is that both are acceptable, but I just wanted to confirm it with you guys, the experts :wink:

When it comes to email, I'd like to be certain.

Thanks