5.7 Summary

• A major difference between legitimate mass mailing and spamming is that the legitimate mass mailers are generally interested in making sure all of their email reaches the intended recipients, whereas spammers don't care.

• For messages with a large number of recipients, the most important factor for improving throughput is making queue operations efficient.

• For messages with a large number of recipients, splitting the qf file can result in faster delivery because several delivery attempts can occur at once. The downside is that it results in more files and often more I/O operations in the queue directory. Optimizing against these two factors can prove quite challenging.

• When sending large amounts of email, the sender has control over how and at what rate the email is injected into the system. This information can be used to improve throughput.