Linux

Screw up your email settings? 🙂 it happens to the best of us.

PLESK has a handy little app that reverts your mailbox settings back to the settings in the PLESK database, and makes sure permissions, etc. are correct.

We encountered this error recently when upgrading our ClamAV to 0.95 and ran into a problem where we got the error :

LibClamAV Warning: Cannot dlopen: file not found – unrar support unavailable

The solution to this is quite simple:

There may come a time where you try to run a command on many files in a folder and you’ll get this annoying message similar to this:

-bash: //bin/chown: Argument list too long

The reason for this annoyance is that Linux kernel has a limitation of bytes it can process through as arguments in exec() commands. Try:

[root@x folder]# egrep ARG_MAX /usr/include/linux/limits.h
#define ARG_MAX 131072 /* # bytes of args + environ for exec() */


And you’ll see what I mean.

This post is inspired by Russ Whittmann and Europheus’ solutions , with these goals/improvements in mind:

• Move spam marked by spamassassin into a special Spam folder in each account (flabergasted this isn’t standard on something like PLESK!)
• Allow for quota, which is available on some PLESK servers (I previously thought it was available on all servers until recently) .
• Make a solution with as minimal manual labour as possible outside the PLESK control panel, which relates most specifically to having to edit and create .qmail and .procmailrc files each time you change or add an email account.
• Avoid having to have a special .procmailrc file for every user, one recipe for all!

It’s possible to have a server act as a backup server, so in the unfortunate event that your main mail server goes down, mail gets queued up on the backup server until the main one is fixed.

Setting up PLESK to act as a backup MX server is fairly easy, here’s what to do.

Here’s some handy tips for managing your qmail queue on a linux machine, which can be helpful for debugging:

I managed to get a little email archiving system working which I am finding to be potentially quite useful in the future. The beauty of it is that every email going in and out the system is saved onto a google gmail account, which harnesses their power of filtering, searching and labelling!

This setup was specifically aimed at a PLESK-run box but I’m sure it would work on any box with a qmail/qmail-scanner enabled mailserver, actually any MTA with a Maildir format.

Qmail-Scanner is a very versatile tool for linux which allows you to scan any email that passes your system with various brands of virus scanners, including the open source ClamAV. Alongside the more thorough scan and possibility to audit content, I find the archiving feature very useful.

One particularly useful bit of qmail-scanner is that you don’t need to recompile qmail for patching, which can be a mamoth task on PLESK run systems (specifically VPSes in Virtuozzo)

I’ve been setting up a Postfix/Dovecot solution on a linux Fedora 9 machine and ran into this problem.

A little snooping around led to this solution:

Dovecot requires the dovecot-mysql package to run mysql authentication. This problem is simply cured by installing it with yum:

yum install dovecot-mysql