qmail's modular, lightweight design and sensible queue management make

it the fastest available message transfer agent. Here's how it stacks up

against the competition in five different speed measurements.

* Scheduling: I sent a message to 8192 ``trash'' recipients on my home

machine. All the deliveries were done in a mere 78 seconds---a rate of

over 9 million deliveries a day! Compare this to the speed advertised

for Zmailer's scheduling: 1.1 million deliveries a day on a

SparcStation-10/50. (My home machine is a 16MB Pentium-100 under BSD/OS,

with the default qmail configuration. qmail's logs were piped through

accustamp and written to disk as usual.)

* Local mailing lists: When qmail is delivering a message to a mailbox,

it physically writes the message to disk before it announces success---

that way, mail doesn't get lost if the power goes out. I tried sending a

message to 1024 local mailboxes on the same disk on my home machine; all

the deliveries were done in 25.5 seconds. That's more than 3.4 million

deliveries a day! Sending 1024 copies to a _single_ mailbox was just as

fast. Compare these figures to Zmailer's advertised rate for throwing

recipients away without even delivering the message---only 0.48 million

per day on the SparcStation.

* Mailing lists with remote recipients: qmail uses the same delivery

strategy that makes LSOFT's LSMTP so fast for outgoing mailing lists---

you choose how many parallel SMTP connections you want to run, and qmail

runs exactly that many. Of course, performance varies depending on how

far away your recipients are. The advantage of qmail over other packages

is its smallness: for example, one Linux user is running 60 simultaneous

connections, without swapping, on a machine with just 16MB of memory!

* Separate local messages: What LSOFT doesn't tell you about LSMTP is

how many _separate_ messages it can handle in a day. Does it get bogged

down as the queue fills up? On my home machine, I disabled qmail's

deliveries and then sent 5000 separate messages to one recipient. The

messages were all safely written to the queue disk in 23 minutes, with

no slowdown as the queue filled up. After I reenabled deliveries, all

the messages were delivered to the recipient's mailbox in under 12

minutes. End-to-end rate: more than 200000 individual messages a day!

* Overall performance: What really matters is how well qmail performs

with your mail load. Red Hat Software found one day that their mail hub,

a 48MB Pentium running sendmail 8.7, was running out of steam at 70000

messages a day. They shifted the load to qmail---on a _smaller_ machine,

a 16MB 486/66---and now they're doing fine.