Open source mail archiving software compared

Locked Away

Archiving Rules

Administrators can handle the configuration in a web GUI, which is optimized for mobile devices. Additionally, CLI commands are available for automation purposes. Piler fundamentally transfers all mail from the data stream to the archive; administrators can define flexible rules based on regular expressions to filter messages with specific features and prevent them from ending up in the archive. Retention rules let the operator define how long messages are kept in the archive before they are automatically discarded (deleted).

Access to Email

Authorizations or searching and access to mail via the web GUI can be assigned at the user and group level (Figure 2). Regular users only get to see their own messages; if desired, the archive can be integrated directly with Outlook.

Figure 2: Piler has a neat administration GUI that is also suitable for mobile devices.

Auditors have access to all mail. Using a separate window, an auditor can access messages in a targeted way and retrieve a log for each email message, providing information on any operations performed on the message in question (e.g., whether the message has been accessed, searched for, or downloaded) (Figure 3). The search is fast and, in addition to an advanced search feature based on a form, offers the option of using search expressions with a highly detailed syntax:

Figure 3: The Audit function supports searching for email messages and provides details on their integrity and history.
size:>.2M, subject: viagra OR cialis, \
  body: order < now, from: my@email.address

This is an example of a complex Piler search that filters out Viagra spam with a message size of more than 200KB and other features.


If you do not want to download and use the prebuilt VMware appliance [2], you will need a little patience installing Piler because the program, which was programmed in C, does not provide any installation packages. On a Linux or Solaris host, you first need to set up the required basic packages: OpenSSL, MySQL 5.1+, Sphinx Search 2.1+, PHP 5.3.x+, web server with rewrite technology (Apache, Lighthttpd, Nginx), TRE Regex Library, Libzip, and Iconv. Then, you can download the source code [3] and build it as follows:

tar zxvf piler-x.y.z.tar.gz cd piler-x.y.z
./configure --localstatedir=/var --with-database=mysql \
  --enable-starttls --enable-tcpwrappers
make su -c 'make install'

After doing so, set up a user named piler and run the postinstallation routine by typing make postinstall; among other things, this will create the databases, generate cronjobs, and create a web directory. Finally, start the Piler daemon and the Sphinx indexer. Initial login via the web GUI uses the admin@local account and the pilerrocks password.

Once you get there, you can start setting up Piler for production. This involves creating users and groups, defining the desired archiving rules, and configuring the required SMTP server so that it passes the incoming mail data stream to Piler. If you have a Postfix mail server, you can do this with the following entry in

always_bcc =

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