This page gives a few pointers in choosing the right hardware for the mail server and also how to configure a router or firewall.
Most connections to the Internet usually involve either a router and/or a firewall. If one is present then you will need to configure it to allow certain ports through to the mail server. This usually involves either accessing the software (software router or firewall) or accessing an HTML interface (hardware router or firewall). Here you will have the option of choosing a port to accept connections on and a destination computer and port which the connection will be routed to. For the mail server to function correctly, the list below describes the default ports which may require forwarding:
| Service | Port | Implicit SSL Port |
|---|---|---|
| SMTP | 25, 587 | 465 |
| POP3 | 110 | 995 |
| IMAP4 | 143 | 993 |
| WebMail | 8000 | 8100 |
| LDAP | 389 | - |
| Remote Admin | 9000 | 9100 |
If you have changed any of the ports then you will need to use your new port value instead. Also, if you have set any bind IPs for any of the services, you must ensure that the destination computer information for the port forwarding is set to the correct IP.
Surprisingly, a server doesn't necessarily have to be a high specification machine. You could minimally host your mails with the following:
1GHz or Higher CPU
2 GB RAM
100GB Hard Drive
Broadband Internet Connection
The main thing that needs to be fast is the Internet connection. However, with a lot of traffic coming into your server you may find a higher specification server more effective. A better configuration could be:
2GHz or Higher CPU (dual or quad core)
4GB High Speed RAM (possibly more with a very busy server)
500GB High Speed Hard Drive (possibly more when storing a large number of mails)
High Speed Broadband Internet Connection (the faster the better)
It's very important to have enough memory on your server as busy servers will always perform much quicker with plenty of memory. Most of the important application data is usually stored in memory. Therefore, the more memory you have, the more applications you can safely run. If your server starts to run low on memory, it will start to use the hard drive more. This is often referred to as page file memory and usually results in the system slowing considerably. If the computer has a good amount of memory, commonly accessed files on the hard drive can be 'cached' into memory to improve general performance. This is intended to help reduce the bottle neck of hard drive access, which compared to normal memory access is very slow. Also, once a system starts to run low on memory and page file use is increased, the system becomes more unstable and is more susceptible to crashes. The 'bottom line' is: 'More memory means a more stable and efficient server'.
To add to the above memory considerations, it is worth noting that with a very busy server, the hard drive is often responsible for bad performance. Ensuring a fast Hard Drive (at least 7200RPM) is a key element of your server's hardware configuration. Additionally, if the server begins to make more use of page files, then a good hard drive will help maintain performance under exceptionally large demands.