Free smtp server software for linux

Net::Server is an extensible, general Perl server engine.
SYNOPSIS
#!/usr/bin/perl -w -T
package MyPackage;
use Net::Server;
@ISA = qw(Net::Server);
sub process_request {
#...code...
}
MyPackage->run(port => 160);
exit;
Main features:
- Single Server Mode
- Inetd Server Mode
- Preforking Simple Mode (PreForkSimple)
- Preforking Managed Mode (PreFork)
- Forking Mode
- Multiplexing Mode using a single process
- Multi port accepts on Single, Preforking, and Forking modes
- Simultaneous accept/recv on tcp, udp, and unix sockets
- Safe signal handling in Fork/PreFork avoids perl signal trouble
- User customizable hooks
- Chroot ability after bind
- Change of user and group after bind
- Basic allow/deny access control
- Customized logging (choose Syslog, log_file, or STDERR)
- HUP able server (clean restarts via sig HUP)
- Dequeue ability in all Fork and PreFork modes.
- Taint clean
- Written in Perl
- Protection against buffer overflow
- Clean process flow
- Extensibility
Net::Server is an extensible, generic Perl server engine. Net::Server combines the good properties from Net::Daemon (0.34), NetServer::Generic (1.03), and Net::FTPServer (1.0), and also from various concepts in the Apache Webserver.
Net::Server attempts to be a generic server as in Net::Daemon and NetServer::Generic. It includes with it the ability to run as an inetd process (Net::Server::INET), a single connection server (Net::Server or Net::Server::Single), a forking server (Net::Server::Fork), a preforking server which maintains a constant number of preforked children (Net::Server::PreForkSimple), or as a managed preforking server which maintains the number of children based on server load (Net::Server::PreFork). In all but the inetd type, the server provides the ability to connect to one or to multiple server ports.
Net::Server uses ideologies of Net::FTPServer in order to provide extensibility. The additional server types are made possible via "personalities" or sub classes of the Net::Server. By moving the multiple types of servers out of the main Net::Server class, the Net::Server concept is easily extended to other types (in the near future, we would like to add a "Thread" personality).
Net::Server borrows several concepts from the Apache Webserver. Net::Server uses "hooks" to allow custom servers such as SMTP, HTTP, POP3, etc. to be layered over the base Net::Server class. In addition the Net::Server::PreFork class borrows concepts of min_start_servers, max_servers, and min_waiting servers.
Net::Server::PreFork also uses the concept of an flock serialized accept when accepting on multiple ports (PreFork can choose between flock, IPC::Semaphore, and pipe to control serialization).

Dwarf Mail Server is a full-featured mail server developed on the Java platform, implementing SMTP, POP3 and IMAP4rev1 protocols.
Dwarf Mail Server provides support for rich application message processing via pluggable mail filters and agents, as well as full handling of virtual domains for the SMTP/POP3/IMAP4 protocols, and is free of charge for the binary redistribution.
Since the server is based on the Dwarf framework, it also shares its common design principles and features - simplicity, high modularity and extensibility, authentication and authorization, XML-based configuration, logging and remote management.
Main features:
- ESMTP, POP3 and IMAP4rev1 implementation
- application logic layer provided by mail filters and agents
- virtual mail hosts in SMTP/POP3/IMAP4 server
- application-independent authentication and authorization
- sample JSP-based webmail interface
Dwarf Mail Server is targeted for both end users who are just looking for simple, secure and robust mail server as well as developers who need an extensible and powerful framework for application message processing.
For users with minimal requirements it can offer portability, simple configuration as well as strong security.
- Portability: several OS platforms are supported via the Java technology, including MS Windows, UNIX/Linux/BSD, MacOS X and others.
- Configuration: just 3 lines have to be changed to fire up a sample mail server and a few of them to run a full featured SMTP/POP3/IMAP4 server.
- Security: it uses Java Platform Security Architecture in combination with Java Authentication and Authorization Service (JAAS), as well as SSL/TLS for the secure communication.
Advanced or enterprise users can additionally appreciate performance scalability, multiple domain handling, enhanced security features and modular design easing to incorporate it to the existing infrastructure.
- Scalability: gaining from multithreaded design and dynamically adjustable allocation of resources.
- Multiple domains: server is able to handle multiple virtual domains in a single instance for all SMTP, POP and IMAP protocols.
- Enhanced security: includes subject-based permissions and access control lists for IMAP, SMTP relaying control rules, host-based filtering, SSL/TLS communication, basic anti-spam filtering, etc.
- Robustness: client/server network communication is by design separated from the resource-expensive application logic layer. The server implementation is based on the unparsed byte streams whenever possible, including its own and highly efficient MIME parser.
Dwarf Mail Server also appears to be a suitable platform for application development and customization. Its modular structure and lightweight API allows enhancing existing functionality or completely exchanging the certain part as a whole:
- Message processing: mail filters and agents provide an unique infrastructure for rich message processing.
- Mail queue: physical mail queue representation is abstracted by the API specification and may replaced by a custom implementation.
- Storage subsystem: physical data representation (i.e. messages, folders, configuration options, ACLs) is abstracted by API and may be replaced by a custom implementation based on filesystem, SQL database, etc.
- MIME parser: the parsing engine may be reimplemented for the top efficiency according to the currently used mail storage.
Dwarf Mail Sever has been tested with the most popular mail clients like MS Outlook, Mozilla, Thunderbird, Opera, Apple Mail, Becky!, Pegasus, Eudora, Pine, The Bat! and others.
Other features:
- multi-threaded server
- dynamically adjusted number of active threads
- server API for mail, user data and ACL storages
- robust SMTP server architecture with flexible queue design
- simultaneous deliveries to remote SMTP hosts
- transparent Delivery System Notification (DSN) mechanism
- support for shared mail folders
- fast and universal stream-oriented MIME parser
- runtime server configuration
- built-in SSL/TLS support
- full documentation with user guides and tutorials
- samples with source code

SMTPHandler is a handler for the java.util.logging library. SMTPHandler sends LogRecords via email using the Simple Mail Transfer Protocol.
The SMTPHandler code is derived from log4js SMTPAppender.
After downloading the SMTPHandler software, you will need to download two additional JAR files:
1) Sun JavaMail
http://java.sun.com/products/javamail
2) Sun JavaBeans Activiation Framework
http://java.sun.com/products/javabeans/glasgow/jaf.html
Enhancements:
- This release adds SMTP server authentication.
- You can specify an SMTP username and SMTP password.

ClamSMTP project is an SMTP filter that allows you to check for viruses using the ClamAV anti-virus software.
It accepts SMTP connections and forwards the SMTP commands and responses to another SMTP server. The DATA email body is intercepted and scanned before forwarding.
ClamSMTP aims to be lightweight, reliable, and simple rather than have a myriad of options. Its written in C without major dependencies. If you need more options then you could use something big like AMaViS which is written in PERL and can do almost anything.
I wrote this with the Postfix mail server in mind. Heres how to configure it as a Postfix Content Filter.
ClamSMTP can also be used as a transparent proxy to filter an entire networks SMTP traffic at the router.
Enhancements:
- Support has been removed for listening on ports under 1024.
- Support has been added for embedded NULLs in email data.
- Problems with not listening properly when in daemon mode have been fixed, as well as warnings when compiled with gcc 4.0.
- Empty addresses are handled properly in logs.
- This release will not let Exchange send its strange binary data through the proxy.
- More Solaris fixes.
- Email messages are not rejected when the server is overloaded or encounters errors, or when starting the filter command fails.

smtpauth is a authenticating proxy for servers without SMTP AUTH.

Use smtpauth and stunnel programs to add SMTP AUTH (PLAIN, LOGIN) support to any SMTP server. Clients can authenticate over SSL port 465 or cleartext port 587, and authentication is fully logged via syslog.

Works with JBMail, Pegasus Mail, Mozilla Thunderbird, MS Outlook...

This software is really an interim solution until our favourite MTA(s) support SSL/TLS and SMTP AUTH directly. For now I prefer using external programs to provide this functionality rather than patching MTA source. I designed this software to work with my Postfix server, but smtpauth also works with sendmail and just about any other SMTP server.

Installation:

1. Compile and install binary.

make
Copy smtpauth to /usr/sbin, owned by root, mode 755

2. Create special user smtpauth with its own group, no login allowed.

Note that smtpauth will immediately exit with an error if invoked as root.
It must be run from a low privilege account, for security.

3. [For SSL, port 465] Configure stunnel.conf. Change domain for your site.

setuid = smtpauth
setgid = smtpauth
debug = auth.notice
client = no

[smtps]
accept = 465
exec = /usr/sbin/smtpauth
execargs = smtpauth domain 127.0.0.1

4. Configure /etc/smtpauth.conf

This file should only be readable by the smtpauth user, since it stores plain
passwords. It consists of single lines containing usernames and passwords with
whitespace separating. Blank lines and comment lines starting # are ignored.

user1 pass1
user2 pass2

5. [For SSL, port 465] Start up stunnel

This will create a server running as smtpauth on port smtps/465. When SMTP clients
connect (SSL/TLS) the smtpauth program is launched and provides authentication
service through to 127.0.0.1:25, as a proxy. Your actual SMTP server will accept
mail because that connection is local. The mail headers will include X-SMTP-AUTH
indicating the username. Success and failures will be logged via syslog.

6. [For cleartext, port 587] Configure cleartext submission service in inetd

Since inetd (when started with -W) also supports wrapping, the smtpauth proxy
can be run straight out of here too. Note that this is somewhat risky, because
there will be no SSL/TLS encryption on the submission port (587).

Again, change domain for your site (e.g. mail.yoursite.tld)

submission stream tcp nowait smtpauth /usr/sbin/smtpauth smtpauth domain 127.0.0.1

POEST::Server - The Poest Master General.

SYNOPSIS

my $server = POEST::Server->new(
Config => POEST::Config::Genearl,
ConfigFile => /etc/poest.conf,
);

$server->start;

ABSTRACT

This module controls the server itself.

All high-level server interaction happens here.

new()

Create a new server instance. This will not make the server run, but it will configure it, load the modules and configure them, and spawn the proper POE sessions. All the parameters passed to new will be passed directly to the configurator of your choice, as defined by the Config parameter (POEST::Config by default).

run()

Make the server run. This will block execution when called directly.

start()

Fork and start the server. This method will return the pid of the server. If the pidfile configuration parameter is found in the configuration class, an attempt is made to write that pid file. If that attempt fails, or if the pid file already exists, and exception is thrown and the attempt to start the server is stalled.

stop()

Stop the server. If a pidfile was specified, the pid will be read from it. Otherwise, an attempt to find a process name with the value of $0 is tried, by default that is set to poest.

NOTE: As of right this minute, the process table magic isnt written as Proc::ProcessTable isnt ported to Darwin.

Configuration

Thses are the configuration parameters that the server itself needs from the configuration mechanism.

hostname

The main host that this smtp server runs for.

port

The port this server will run on.

plugin

This is a multi-value parameter. Each value is the full name of the module that contains the plugin class.

libESMTP is an SMTP client which manages posting (or submission of) electronic mail via a preconfigured Mail Transport Agent (MTA).
libESMTP library may be used as part of a Mail User Agent (MUA) or other program that must be able to post electronic mail but where mail functionality is not that programs primary purpose.
The availability of a reliable lightweight thread-safe SMTP client eases the task of coding for software authors thus improving the quality of the resulting code.
Main features:
- libESMTP supports many SMTP extensions, notably PIPELINING (RFC 2920), DSN (RFC 1891) and SASL authentication (RFC 2554). SMTP AUTH is implemented using a SASL client library integrated into libESMTP. Supported SASL mechanisms include CRAM-MD5 and NTLM.
- libESMTP is also efficient. Because it buffers all network traffic, when used in conjunction with a pipelining SMTP server libESMTP significantly increases network performance, especially on slow connections and those with high latency. Even without a pipelining server libESMTP offers significantly better performance than would be expected with a simple client.
- libESMTP is not designed to be used as part of a program that implements a Mail Transport Agent. This is not because the code is unsuitable for use in an MTA, in fact the protocol engine is significantly better than those in many MTAs. Rather, by eliminating the need for MX lookup and next-hop determination, the design of libESMTP is simplified; thus goals are made achievable. Besides, such features are undesirable in a program that is not an MTA, particularly if the client is behind a firewall which blocks access to port 25 on the Internet.
Enhancements:
- This release applies bugfixes and plugs some memory leaks.
- It also attends to a few autoconf-related issues.