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- 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.
-