How can e-mail get through a firewall to a microsoft windows sbs server?

doesn't the firewall block all attempts inward?

How can e-mail get through a firewall to a microsoft windows sbs server?windows vista ultimate

The firewall will allow the email to go through if you write a specific rule to allow it. How to write the rule(s) depends on the firewall you are using and the prots you are utilizing for email. See the firewall administrators guide to find out how and where to write such a rule.