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Setting the maximum mail size in qmail

Major Hayden — Mon, 24 Mar 2008 18:54:35 +0000

On a Plesk server, the maximum size for an individual e-mail sent through qmail is unlimited. You can limit this size by adding a number to the /var/qmail/control/databytes file.

If you wanted to limit this to something like 10MB, you can just run the following command:

echo "10485760" > /var/qmail/control/databytes

This will limit the size of messages (including attachments) to 10MB as a maximum.

Setting the maximum mail size in qmail is a post from: Major Hayden's Racker Hacker blog.

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Reduce iowait in Plesk: put qmail's queue on a ramdisk

Major Hayden — Fri, 14 Mar 2008 18:16:57 +0000

I really dislike qmail. But, since I use Plesk, I'm stuck with it. However, I found a way to improve it's awful mail queue performance by putting the mail queue onto a ramdisk. This is actually pretty darned easy to do.

First, toss a line like this into your /etc/fstab:

none    /mailqueue      tmpfs   defaults,size=100m,nr_inodes=999k,mode=775      0       0

This will make a 100MB ramdisk on /mailqueue. Now, just symlink /var/qmail/mqueue to /mailqueue and move your e-mail over:

# mount /mailqueue
# chmod 750 /mailqueue
# chown qmailq:qmail /mailqueue
# mv /var/qmail/mqueue /var/qmail/mqueue-old
# ln -s /mailqueue /var/qmail/mqueue
# rsync -av /var/qmail/mqueue-old /mailqueue

This has significantly cut the iowait on my server during heavy e-mail periods. In addition, tools like qmHandle now fly through my mail queue and give me reports very quickly.

Reduce iowait in Plesk: put qmail's queue on a ramdisk is a post from: Major Hayden's Racker Hacker blog.

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Can't enable DNSBL/RBL in Plesk because it's greyed out

Major Hayden — Fri, 25 Jan 2008 17:11:27 +0000

If you have a new Plesk installation and the following option is greyed out in Server -> Mail: Switch on spam protection based on DNS blackhole lists Just install the following RPM from Plesk: psa-qmail-rblsmtpd Can't enable DNSBL/RBL in Plesk because it's greyed out is a post from: Major Hayden's Racker Hacker blog. Thanks for [...]

Can't enable DNSBL/RBL in Plesk because it's greyed out is a post from: Major Hayden's Racker Hacker blog.

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qmail: This message is looping: it already has my Delivered-To line

Major Hayden — Wed, 23 Jan 2008 18:20:27 +0000

I stumbled upon this peculiar bounce message recently while working on a server:

Hi. This is the qmail-send program at yourmailserver.com. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out.


:

This message is looping: it already has my Delivered-To line. (#5.4.6)
--- Below this line is a copy of the message.

Return-Path: Received: (qmail 14418 invoked by uid 110); 9 Jan 2008 13:04:33 -0600 Delivered-To: 54-user2@domain.com Received: (qmail 14411 invoked by uid 110); 9 Jan 2008 13:04:33 -0600 Delivered-To: 53-user1@domain.com Received: (qmail 14404 invoked from network); 9 Jan 2008 13:04:33 -0600 Received: from otherdomain.com (HELO otherdomain.com) (11.22.33.44) by yourmailserver.com with SMTP; 9 Jan 2008 13:04:33 -0600

Basically, this is qmail's way of letting you know that your e-mails are stuck in a mail loop. One e-mail user is redirecting to another e-mail user, and that e-mail user is redirecting back to the first one. If q-mail already has a delivered to line which matches one that it already added, it bounces the e-mail and halts delivery.

qmail: This message is looping: it already has my Delivered-To line is a post from: Major Hayden's Racker Hacker blog.

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Plesk and qmail: 421 temporary envelope failure (#4.3.0)

Major Hayden — Tue, 04 Dec 2007 18:21:23 +0000

I stumbled upon a server running Plesk 8.2.1 where a certain user could not receive e-mail. I sent an e-mail to the user from my mail client, and I never saw it enter the user's mailbox. It didn't even appear in the logs.

After checking the usual suspects, like MX records, mail account configuration, and firewalls, I was unable to find out why it was occurring. Even after a run of mchk, the emails would not be delivered.

I began testing with a telnet connection to the SMTP port:

$ telnet 11.22.33.44 25 Trying 11.22.33.44... Connected to 11.22.33.44. Escape character is '^]'. 220 www.yourserver.com ESMTP HELO domain.com 250 www.yourserver.com MAIL FROM: test@test.com 250 ok RCPT TO: someuser@somedomain.com 421 temporary envelope failure (#4.3.0) QUIT 221 www.yourserver.com Connection closed by foreign host.

Temporary envelope failure? I was still confused. After reviewing the logs, I found the following line whenever I tried to telnet to port 25 and send an e-mail:

Dec 2 00:15:49 www relaylock: /var/qmail/bin/relaylock: mail from 44.33.22.11:17249 (yourdesktop.com)

It turns out that the customer was using greylisting in qmail with qmail-envelope-scanner. After a quick check of /tmp/greylist_dbg.txt, I found the entries from me (as well as a lot of other senders), and that ended up being the root of the problem.

Plesk and qmail: 421 temporary envelope failure (#4.3.0) is a post from: Major Hayden's Racker Hacker blog.

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Sort e-mail in Plesk with procmail

Major Hayden — Tue, 27 Nov 2007 18:27:26 +0000

One of my biggest beefs with Plesk's e-mail handling is the lack of server-side filtering. Plesk will only allow you to throw away e-mails marked as spam, but this won't work for me since SpamAssassin marks some mails as spam that actually aren't. If you set up filters in SquirrelMail or Horde, the filters will only work if you always log into the webmail interface to snag your e-mail.

Luckily, you can do some fancy work with procmail to have the filtering done server-side.

First, make sure procmail is installed on your server, and change to this directory:

/var/qmail/mailnames/yourdomain.com/yourusername/

Inside that directory, drop in a .procmailrc file which contains the following:

MAILDIR=/var/qmail/mailnames/yourdomain.com/yourusername/Maildir DEFAULT=${MAILDIR}/ SPAMDIR=${MAILDIR}/.Junk/ :0 * ^X-Spam-Status: Yes.* ${SPAMDIR}

Once that file is in place, move the .qmail file out of the way, and replace it with this:

| /usr/local/psa/bin/psa-spamc accept |preline /usr/bin/procmail -m -o .procmailrc

Please be aware that these changes will disappear if you make any adjustments to your mail configuration within Plesk. To get around this annoyance, just change the file attributes to immutable:

# chattr +i .qmail .procmailrc

Credit for this trick goes to Russ Wittmann.

Sort e-mail in Plesk with procmail is a post from: Major Hayden's Racker Hacker blog.

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