Once you have installed CMSB in a business environment, there is some configuration you will need to perform explicitly to allow CMSB to be accessible remotely (i.e. outside the LAN in which it's installed)

The key to remote access is configuring your firewall so that incoming connections on ports 110, 25, and 8080 are forwarded to the server on which CMSB is running. Note by the way that you can change these ports in CMSB, and indeed you may have to change port 25 to something else to enable remote users to get to it because a number of ISPs now block consumers from connecting to external servers on port 25. However, for the purpose of this article, we will assume that you will use 110, 25, and 8080.

This article presumes that you have an understand of TCP/IP, networks, firewalls, DNS and so forth and does not attempt to explain the HOW of these operations.

Once you have configured your firewall to allow remote access, the second step is to give CMSB permission to allow remote users to connect. This is done by clicking on Setup | Main | General, selecting Advanced in the left window pane and then clicking on the Change Access Permissions button to bring up the IP Address Control window.

ALthough you have a number of options, it's generally safe to enable "Block specified connections", which, without actually entering any IP address ranges, will allow anyone to connect. The reason this is safe is because without knowing the username and passwords to check mail, CMSB will not let you SEND any mail, therefore you are not in danger of of CMSB becoming an "open relay" for spammers. (Make sure you use decent passwords though)

Having said that, we have found from experience that there are a few address ranges worth blocking completely to simply prevent connections. For example, if you wish to block any connections starting with 210 (One of the Asia Pacific regions), then you would enter 210.*.*.* as the address range. From experience, we have found it worthwhile adding the following ranges:

* 61.*.*.*
* 80.*.*.*
* 202.*.*.*
* 203.*.*.*
* 210.*.*.*
* 211.*.*.*
* 213.54.*.*
* 218.*.*.*
* 219.*.*.*
* 220.*.*.*
* 222.*.*.*

Depending on the region of the world you are in, and from where you need to connect, you may wish to change these. It's worth monitoring the activity logs for a while to see from what IP addresses connection attempts occur and then block those. Note - it's not worth blocking explicit IP addresses - better to determine the most general range associated with the actual connection. We use a program called Smart WhoIs from TamoSoft for this purpose but there are many programs as well as free websites that you can use to determine the origin of an IP address.

Incidentally, if you do find you are being probed from many places, that's a good reason to use non-standard values for your POP3 and SMTP ports.

The final step is configuring remote email programs to access the ChoiceMail server. You already know from the standard documentation that in your email program you will need a username and password where the username is normally the combination of your ChoiceMail username followed by a slash followed by an actual email address. (see manual configuration)
The server for both incoming and outgoing mail will be the IP address of your CMSB as seen from the outside world. In other words, it will be the external IP address that is assigned by your internet provider. If that external address is static, you can just hardcode the address into email programs. However, if the address is dynamic, then you will need to use a service that can provide you with a name that will be associated on the fly with the currently assigned dynamic IP address. There are many such services available (free and paid) and a websearch for "dynamic IP name server" will indicate many possibilities - however we have had excellent success with DynDNS.

* Changing listening ports To change the SMTP connection port on which CMSB listens for incoming connections from remote email clients, click on Setup | Main | General and change the value in the SMTP Proxy Connection section.
* To change the POP3 connection port, click on Setup | Main | General (you may already be there from above), then click on POP3 Server on the left window pane. Then change the value in the "Listen on port" to the desired value.
* To change the HTTP connection port - click on Setup | Main | General (you may already be there from above), then click on HTTP Settings on the left hand side. Then change the value in the "Listen on port" to the desired value.