Amavis is a server-side virus scanner written in the Perl programming language and used on Unix mail servers. If an unwanted e-mail is detected, Amavis automatically removes it from circulation. The reliable program now also blocks spam messages that would otherwise fill the mail server. This useful tool saves a lot of time and the settings options leave plenty of room for individual mail server configuration.
SpamAssassin reliably switches off viruses
An important part of Amavis is the SpamAssassin module. Regardless of the number of recipients entered, this spam blocker checks whether the message fits into the preset spam category or not. This way, the mail server is not overly burdened with this task and all incoming messages are instead efficiently processed centrally according to the wishes of the individual recipient. In general, the combination of spam blocker and virus scanner works very resource-saving. Amavis was written in the Perl programming language, with a special focus on preventing buffer overflows while providing administrators with simple maintenance options. Amavis does not see itself primarily as a virus scanner, but more as an interface that can be extended with antivirus programs such as SpamAssassin, ClamAV, Kaspersky LMS or AVG AV. Within this framework, threats to the mail server, as well as to the work computers, can be detected and prevented with minimal time. Amavis is able to archive or quarantine messages. These can be stored either in a mailbox or in an SQL Database can be transferred. It is also possible to create a DKIM signature with Amavis. This identification protocol ensures that the mail is authenticated. This prevents mail spoofing, which always causes serious security problems. Amavis supports a variety of different MTA settings. In general, the server admin has a lot of settings at his disposal and can assign mail recipients to individual subgroups, which in turn work according to their own rules. For example, it is possible to receive spam messages with their own header notification, which is tailored to the respective recipient.
Amavis convinces with good performance
Although Amavis was written in the Perl programming language, the software can still convince with a good performance. This is mainly due to the fact that large blocks of data are not scanned line by line, unnecessary copying of files has been prevented and the developers have shown a keen sense of optimization. In combination with the aforementioned antivirus programs, one should nevertheless pay attention to which e-mails should be subjected to a closer examination. Especially if the required identifier is available, exceptions can be defined to allow for quick and timely processing. Amavis is primarily committed to the defined RFC standards. Some of the project's beginnings date back to 1997. Incoming messages are forwarded to the Mail Transfer Agent using the well-known SMTP and LMTP protocols. If an unexpected event occurs during the mail transfer, a series of measures immediately take effect to secure the message. With this set of measures, Amavis prevents mail from being lost or messages from being rendered unreadable due to a crash. Messages are not kept in memory, which should prevent too large messages from causing a crash or serious server problems. The only exception is the transfer to the virus scanner SpamAssassin, but this is due to the way the scanner works. This can be prevented by using the Administrator sets a size limit on files so that messages above a certain size are not forwarded to the module and have to undergo a separate check instead As with other mail server interfaces, certain senders can be entered in a black or white list. This saves the mail server the work and allows it to sort out senders that have caused problems in the past or that do not need to be checked. All in all, Amavis puts together a convincing software package that can easily be extended with additional modules or virus scanners and proves to be a useful interface.
