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

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

     3 against the competition in five different speed measurements.

     4 

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

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

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

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

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

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

    11 accustamp and written to disk as usual.)

    12 

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

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

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

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

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

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

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

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

    21 per day on the SparcStation.

    22 

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

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

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

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

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

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

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

    30 

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

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

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

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

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

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

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

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

    39 

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

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

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

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

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