Chapter 3. Tuning Email Relaying

Often a server running sendmail acts as a gateway between the Internet and one or more internal email systems. If a site has a high-bandwidth connection to the Internet, and the network includes multiple internal email servers, then a gateway machine can easily become saturated with requests. Even if the network bandwidth available is small, a failure of some link in the local network, the Internet connection, a local mail server, or even a large remote email server can cause a tremendous amount of email to back up in the gateway's queue. These kinds of events can cause serious problems for a gateway email server. Luckily, some techniques are available to mitigate the damage.