These figures are derived from the daily statistics reports that L-Soft generates for its EASE and ListPlex^® list hosting services. Every single message was actually delivered through a real mailing list with real subscribers all over the world. The numbers were not "pumped up" using test messages, unrealistic LAN-speed test environments or extrapolations.

All these machines are running LISTSERV^® and LSMTP^®.

The PLUM cluster is a redundant OpenVMS cluster with automatic failover. Outbound messages can be directed to an individual node, with failover to the other nodes, or to the cluster as a whole, with load balancing.

• Every day, shortly after midnight, we generate a statistics report for each of our mail delivery servers. These reports cover the previous day's activity, from midnight to midnight.

• At the same time, we prepare the yearly record reports that you have seen on this page. The daily statistics reports for the current year are scanned and the best figure in each category is copied to the record report, along with the date at which it was recorded.

• Highest total deliveries (one day) refers to the total number of messages delivered from midnight to midnight by the machine in question. This figure gives you an idea of how much mail you can deliver on a single machine with LISTSERV and LSMTP. Yes, we deliver millions of messages every day on a single machine!

• Highest sustained delivery rate for 1 minute is the largest number of messages that the machine was able to deliver in the space of one minute, divided by 60 seconds. In other words, if the published figure is 400/sec, it means the server actually delivered 24,000 messages in one particular minute, which averages to 400/sec.

  This figure gives you an idea of how quickly you can deliver urgent messages. Let's say that you need to deliver one urgent message every day to 500,000 subscribers. To do this, you obviously need a daily capacity of 500,000 deliveries or more, but this is not sufficient. A machine with a capacity of 500,000 daily deliveries could have a delivery rate as low as 5.8 messages per second. If you want to reach 500,000 subscribers in 30 minutes, you will need a sustainable delivery rate of at least 278/sec.

• Highest sustained delivery rate for 5 minutes is similar, but refers to a 5-minute period. In some cases, the figure is much lower because the server ran out of incoming mail in less than 5 minutes. For instance, to sustain a delivery rate of 400/sec for 5 minutes, you need to have 120,000 messages to deliver, each going to hosts which are currently reachable and reasonably fast. Even if you routinely deliver 3,000,000 messages per day, it is unlikely that you will have received 120,000 of these messages in just 5 minutes.

• Highest traffic in a one-hour period is again the same thing, but over a much longer period of time. Here you are almost always limited by the number of messages that you have, rather than by the speed of the machine. To sustain 400 deliveries per second for an entire hour, you would need to have 1,440,000 messages that need to be delivered in the first place.