SMTP: Recommended Environments for the SMTP Gateway

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1. The postoffice (PO) and gateway should be on the same physical network. Because the gateway's temporary files are written on the postoffice (M:\MAILDATA\SMTP\), and not its local hard disk, the performance of the gateway is dependent on file input/output. The most effective way to ensure fast file input/output is to have both the gateway and postoffice on the same physical network.
2. Use a Mail Relay Host for inbound SMTP mail. It is not mandatory to have Mail Relay Host configured for Inbound mail, but it is highly recommended. The SMTP Gateway is dependent on a MS-DOS redirector and the reliability of a UNIX to MS-DOS connection is not as robust as that of a UNIX to UNIX connection (UNIX is multithreaded; MS-DOS is single threaded). Therefore, you should control the UNIX to MS-DOS connection by storing all messages going to the Microsoft Mail on a Host before they get forwarded to Microsoft Mail.
   
   You want to have as much control over the less reliable UNIX to MS-DOS connection as possible. The optimum way to control this is by putting a Mail Relay Host on the same network segment as the gateway and PO server. Not only does this increase the reliability of the UNIX to MS-DOS connection from a physical perspective, but it also allows the Host to be configured to open/close the connections more effectively.
3. Routers should use static routing. If the Smart Host (Mail Relay Host) is not on the same network segment as the gateway and PO, then static routes should be configured on the router that separates the gateway and host. The IP addresses for the gateway and the Smart Host should be added to the static table on the router.
   
   NOTE: Most routers use dynamic routing by default, a static table needs to be manually created and maintained.
4. Use a 16-bit network interface card (NIC) When you use a 16-bit NIC, it is a good way to get fast file input/output. Additionally, it is recommended to use a 16-bit NIC with RAM disabled.
5. Use one protocol per NIC (IPX/SPX) When the PO is on a Novell NetWare server, and IPX/SPX is used to access the PO and TCP/IP is used to access the Host, it may be necessary to isolate each protocol on a separate NIC.