reads a configuration file when starting up. The location of the file is dependent on how you compiled clamsmtp but it should usually be in either the /usr/local/etc/ or /etc/ directories. If clamsmtpd() does not find its configuration file it'll print a warning when it starts up along with the location it's expecting to find it in. You can also specify a different location for a config file by passing the -f argument to clamsmtpd()

The settings are specified one per line. The setting names come first, followed by a colon and then the value. Comments start with the '#' character on a line of their own. Whitespace is ignored at the beginning of line, end of line and around the colons.

A sample configuration file can be found in the doc/ directory of the clamsmtp distribution.

The various settings are as follows:

Bounce

When this flag is set clamsmtpd() actively rejects messages with viruses. This may cause the sender to receive a message back notifying them of the virus. In most cases this is not a good idea since many viruses spoof sender addresses. [ Default: off ]

ClamAddress

Specifies the address to connect to clamd() on. See syntax of addresses below. [ Default: /var/run/clamav/clamd ]

Header

A header to add to scanned messages. Put an empty value to suppress adding a header. You can include the following special formatting characters in the string to include special values:

%i

Client IP Address

%l

Local IP Address

%d

Current Date

You can also include the standard \r or \n escapes. [ Default: 'X-Virus-Scanned: ClamAV using ClamSMTP' ]

KeepAlives

On slow connections the server will sometimes timeout before clamsmtpd() is finished scanning the file. This option sends NOOP's to the server to keep the connection alive. Specify the number of seconds, or 0 to disable. [ Default: 0 ]

Listen

The address and port to listen for SMTP connections on. See syntax of addresses below. [ Default: port 10025 on all local IP addresses ]

PidFile

Specifies a location for the a process id file to be written to. This file contains the process id of and can be used to stop the daemon. If the -p argument is passed on the command line, then this setting will be ignored. [ Default: none ]

Quarantine

Quarantine files that contain viruses by leaving them in the TempDirectory directory. The file names look like this (where X is a random character or number): virus.XXXXXX [ Default: off ]

MaxConnections

Specifies the maximum number of connections to accept at once. clamd() also needs to be setup to accept at least this number of connections. [ Default: 64 ]

OutAddress

The address of the SMTP server to send email to once it's been scanned. See syntax of addreses below. [ Required ]

TempDirectory

The directory to write temp files to. This directory needs to be accessible to both clamd() and clamsmtpd() [ Default: /tmp ]

TimeOut

The number of seconds to wait while reading data from network connections. [ Default: 180 seconds ]

TransparentProxy

This option enables transparent proxy support, which allows you to route all SMTP traffic that's going through a gateway through clamsmtp which will then send it on to its final destination. This setup usually involves firewall rules which redirect traffic to clamsmtp, and the setup varies from OS to OS. [ Default: off ]

User

The user to run as. If this option is specified then clamsmtpd() must be started as root. It will then drop root privileges and run as the specified user. The user can either be a name or a numerical user id. [ Optional ]

VirusAction

This is a command to run when a virus is found. See the VIRUS ACTION section in clamsmtpd() for a discussion of this option. [ Default: off ]

XClient

Send an XCLIENT command to the receiving server. This is useful for forwarding client addresses and connection info to servers that support this feature. [ Default: off ]

Addresses can be specified in multiple formats:

•

Unix local addresses can be specified by specifying their full path. (ie: '/var/run/clamav/clamd').

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IP addresses can be specified using dotted notation with a colon before the port number (ie: '127.0.0.1:3310').

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IPv6 addresses are implemented but disabled. The code needs testing.