List performance: time to forward one SMTP message with 1000, 2000 and 5000 different remote destinations. Outbound SMTP concurrency = 100. dests 1000 2000 5000 time per 1000 ============================================= qmail 15 32 80 16 mx 13 25 (*) 13 (*) message sink host saturated under the load Local delivery performance: time to deliver 100 SMTP messages to one recipient. Outbound SMTP concurrency = 100, inbound SMTP concurrency = 5, 10, 20. concur 5 10 20 average time ============================================ qmail 62 59 58 60 mx 24 24 25 24 Relay performance: time to forward 100 SMTP messages with one recipient. Outbound SMTP concurrency = 100, inbound SMTP concurrency = 5, 10, 20. concur 5 10 20 average time ============================================ qmail 56 54 54 55 mx 17 19 20 19