Qgreylistrbl is a qmail add-on designed to aid in filtering spam and graylisting incoming emails.
When greylisting is applied, the software returns a temporary SMTP error at the first delivery attempt. This blocks most spam sent from bulk mailers that don't retry. Real mail servers will retry later after receiving a temporary error, allowing the message to go through. However, some emails cannot be delayed for half an hour or longer to customers. This is why qgreylistrbl provides modifications to the program which allow for the delay of only dial-in lines and RBL listed nodes, with a separate cronjob script handling the cleanup instead of the software itself.
Qgreylistrbl creates a directory structure for efficient performance unlike qgreylist from Jon Atkins which puts all files in one base directory. Additionally, most bulk mailers and zombies do not have queue management. This is because most email programs are not equipped to handle the volume of emails they send. An example is that while some users might use a UW-160 Raid 10 for the queue, typical zombies only have one IDE disc. This makes qgreylistrbl more efficient and prone to fewer errors than most other comparable software.
The effect of using qgreylistrbl is that you'll experience up to 80% less spam with no false positives and zero email loss. The software is also easy to use. All you have to do is replace rblsmtpd by D.J. Bernstein with qgreylistrbl in the command line for starting qmail-smtpd.
However, users should expect some CPU usage with qgreylistrbl since it is a Perl script. This can be mitigated by running a QMAILQUEUE-patched version of qmail-smtpd and spamassassin. Users can also precompile the source code with perl>5.6.1 to compensate for this.
The installation process for qgreylistrbl is straightforward. Copy the Perl script to where you want it, edit the start script for qmail-smtpd, and create the greylist IP folder. Users should also adjust a few variables such as the hostname, working directory, some paths, and RBL services. A crontab entry should also be added to perform regular cleanups. Finally, users must set up the logging facility in /etc/syslog.conf for error messages.
Overall, qgreylistrbl is a powerful and effective software that any user can use to minimize spam. It comes with bug fixes, though vpopmail support has been removed due to performance reasons. All you need is a working Perl version, and you can enjoy seamless email management.
Version 0.5: N/A