First besure your Certificate is created and a FQDN

Example servername.yourdomain.com
(You may need to have a subdomain created where you host and point this to
your external IP)

Next make sure ports are open.

Ports
     Table A: Ports that Enable Remote Access to SBS Services
     TCP Port Service Description
     21 FTP Enables external and internal file transfer
     25 Exchange Server Enables incoming and outgoing SMTP mail
     80 (http://) IIS Enables all nonsecure browser access, including:
internal access to IIS Webs including the company Web, Windows SharePoint
Web, Windows SharePoint administration Web, and server monitoring and usage
reports Enables internal access to Exchange by OWA and OMA clients
     110 POP3 Enables Exchange to accept incoming POP3 mail
     123 (UDP port) NTP Enables the system to synchronize time with an
external Network Time Protocol (NTP) server
     143 IMAP4 Enables Exchange to accept incoming IMAP4-compliant messages
     220 IMAP3 Enables Exchange to accept incoming IMAP3-compliant messages
     443 (https://) Outlook Enables all secure browser access, including
external access to Exchange for Outlook 2003, OWA, and OMA clients; required
for external access to server monitoring and usage reports
     444 Windows Share Point Services Enables internal and external access
to the SharePoint Web
     500 IPSec Enables external VPN connections by using IPSec
     1701 L2TP clients Enables external L2TP VPN connections
     1723 PPTP clients Enables external PPTP VPN connections
     3389 Terminal Services Enables internal and external Terminal Services
client connections
     4125 (Note: you can change this port in RRAS) Remote Web Workplace
Enables external OWA access to Exchange, plus internal and external HTTPS
access to the client Web site
     4500 IPSec Internet Key Exchange (IKE) Network Address Translation
(NAT) traversal

Once the ports are open

Run CEICW Wizard (Internet Connection Wizard)

Make sure you have Services enabled...

Go to https://servername/Remote or https://ExternalIP/Remote if you are
outside your intranet.
and click on Configure Outlook via the Internet

Configure Outlook 2003  With that information..
(I will look similar to below but your server will have it's own unique
properties Do not follow below just to show you what it looks like)

Using Outlook via the Internet
If you are using Microsoft® Office Outlook® 2003, you can connect to the
computer running Windows® Small Business Server through the Internet using
the feature called RPC over HTTP. This means you can remotely access your
server e-mail account from the Internet when you are working outside your
organization's firewall. You do not need security-related hardware or
software (such as smart cards or security tokens), and you do not have to
establish a virtual private network (VPN) connection to the server.

Comparing RPC over HTTP and Outlook Web Access
When using RPC over HTTP to access your mailbox, you get the full
functionality of Outlook 2003. For example, you can work offline, use
Microsoft Office Word 2003 as your e-mail editor, and easily organize your
mailbox.

To use Outlook via the Internet
Ensure that the following requirements have been met on the client computer:

Verify that the computer is running Microsoft Windows XP Service Pack 1 or
later
 a.. Click Start, right-click My Computer, and then click Properties.
 The version of the operating system and service pack is displayed under
System. If you do not see a service pack version, there is no service pack
installed.
Verify that Windows update Q331320 is installed on the computer (not
required if you are running Windows XP Service Pack 2 or later)
 1.. Click Start, click Control Panel, and then open Add or Remove
Programs.
 2.. Under Currently installed programs, search for the item Windows XP
Hotfix (SP2) Q331320.
 3.. If the item is not present, go to the Microsoft Web site
(http://go.microsoft.com/fwlink/?LinkId=18651) and follow the instructions
to download and install it.
Verify that the computer is running Outlook 2003 or later
 1.. Open Outlook.
 2.. Click the Help menu, and then click About Microsoft Office Outlook.
The version number appears at the top of the box.
Verify that the computer trusts the certificate used by the server
 1.. Open Internet Explorer, and then in the address bar type:
 https://SmallBusinessITSupport.com/remote

   a.. If the certificate is trusted, a certificate warning does not
appear. In this case, continue with step 1 under Ensure that you have an
Outlook profile configured for the server.
   b.. If the certificate is not trusted, a warning appears. Click View
Certificate, click Install Certificate, and then follow the instructions.
Ensure that you have an Outlook profile configured for the server
 1.. Click Start, and then click Control Panel.
   a.. If you are viewing Control Panel in the default Category view,
switch to Classic view, and then double-click Mail.
   b.. If you are viewing Control Panel in Classic view, double-click Mail.
 2.. In the Mail Setup dialog box, click Show Profiles. If your profile
appears in the list, select your profile, click Properties, click E-mail
Accounts, select View or change existing e-mail accounts, and then click
Next. If your profile does not appear, open Outlook and follow the
instructions to create a profile before proceeding.
   a.. If Microsoft Exchange Server does not appear in the list, the
existing profile is not associated with a Microsoft Exchange Server e-mail
account. Click Cancel, and then click Close. Continue with step 3 to add a
profile.
   b.. If there is an existing Microsoft Exchange Server profile, continue
with step 3 under Configure the computer for RPC over HTTP.
 3.. Click Add. The New Profile dialog box appears.
 4.. In the Profile Name box, type a name for the new profile, and then
click OK. The E-mail Accounts dialog box appears.
 5.. Under E-mail, select Add a new e-mail account, and then click Next.
The Server Type dialog box appears.
 6.. Click Microsoft Exchange Server, and then click Next.
 7.. Continue with step 4 under Configure the computer for RPC over HTTP.
Configure the computer for RPC over HTTP
 1.. Click Start, and then click Control Panel.
   a.. If you are viewing Control Panel in the default Category view,
switch to Classic view, and then double-click Mail.
   b.. If you are viewing Control Panel in Classic view, double-click Mail.
 2.. In the Mail Setup dialog box, click E-mail accounts, click View or
change existing e-mail accounts, and then click Next.
 3.. In the E-mail accounts dialog box, click Microsoft Exchange Server,
and then click Change.
 4.. In the Microsoft Exchange Server box, type the local name of the
Exchange server:
 sbs2003.smallbusiness.local

 5.. In the User Name box, type the user name that you use to log on to the
Remote Web Workplace. Do not click Check Name.

 6.. In the Exchange Server settings page, click More Settings.
 7.. On the Connection tab, under Exchange over the Internet, select
Connect to my Exchange mailbox using HTTP, and then click Exchange Proxy
Settings. The Exchange Proxy Settings dialog box appears.
 8.. Under Use this URL to connect to my proxy server for Exchange, type
the following URL:
 SmallBusinessITSupport.com

 9.. Select Connect using SSL only, and then select Mutually authenticate
the session when connecting with SSL.
 10.. In the Principal name for proxy server box, type the following text:
 msstd:SmallBusinessITSupport.com

 11.. Select On slow networks, connect using HTTP first, then connect using
TCP/IP.
 12.. Under Proxy authentication settings, select Basic Authentication.
 13.. Click OK, and then click OK again. Click Next, and then click Finish.
Click Close.
 14.. In the Mail dialog box, if Always use this profile is selected,
choose the newly configured profile.
 15.. Open Outlook and type your Windows Small Business Server user name
(in the format SMALLBUSINESS\user name) and password. You can now work with
your Outlook mailbox.
Doing all theses things it should work. (I don't think I forgot anything?)

Russ