Free mailservers software for linux

Mailody is a Qt/KDE based mail client which only supports the IMAP protocol. It supports tabbed email reading. This is the first release. I want to have feedback about all the problems. To which mailservers can Mailody not talk for example. Are there any crucial bugs which renders the software unusable for you.
By the way, that is something different as experimental. Mailody should not trash your mail or do other nasty things. I understand mail is important to you. I use Mailody on a daily bases and I would not do that if its buggy.
Enhancements:
- rewrite of large parts of the imap part.
- fetch mailboxlist removed, sync is improved.
- new attachment list in the composer.
- added a re-edit, makes resend possible.
- added a save as draft to the composer.
- added a possibility to add a automatically generated html part to each message.
- fixed bug in selecting the correct profile for forwarding messages.
- stopped stripping the signature when forwarding a message.
- fixed quick search when switching folders.
- Speed improvement for opening folders.
- Fixed drawing error on first messages.
- Added go-to-next-unread.
- Added the possibility to save a message to disk.
- Added fixed font mode for the composer.
- Fixed rare bug in quoted printible messages.
- Improved signature handling.
- Extended the command line parameters & dcop.
- Added a basic phising check.
- Fix some encoding issues in subject and name.
- Most important: ** A MANUAL ** by Richard Johnson.

maRBL project is a policy daemon for Postfix that lets you trigger any Postfix action as a result of an RBL match.

There are only a couple good, practical options for spam filtering, but none of them are 100% effective. Statistical filters can come very close to perfection, but at the cost of CPU time -- you cant filter something until youve received it and spent some time analyzing it -- and there are few good options for blocking hosts outright.

What about RBLs?
RBLs are simple, fast and efficient but they frequently have false positives. Theres an implicit level of trust required: you have to trust RBL administrators to add and remove hosts in a timely and accurate fashion from their lists. The problem is that only a fraction of lists are entirely automated, mosts have humans involved in the process, and humans are fallible. Worse, humans are vindictive, many lists go for collateral damage by blocking large ranges of IP addresses in an effort to arm-twist ISPs into being more responsive about their spam problem.

What about Greylisting?
Greylisting relies on the fact that most spam is no longer sent through real mail servers, and instead is sent from subpar SMTP engines. Greylisting forces senders to wait for a period of time and retry, something many of these engines are incapable of. The problems are that it fares poorly when handling mail from large ISPs that have SMTP clusters (theres no guarantee that the retry will come from the same IP address), that it introduces more delay to the process of receiving an email, and that occasionally you will run across non-RFC compliant mailservers that treat a temporary delivery failure as a permanent one.

SpamFirewall is a mail server filter script that automatically blocks mail servers that send too much spam.
This first version of the software is alittle hard coded. I want to make it more
modular with a client/server setup, plugins for different firewall systems, and
plugins for spam matching. At present however its geared toward postfix, iptables
and spamassassin.
To run te firewall make these steps:
Run spamfirewall.sql against your mysql server. Or the update sql patches.
Modify spamfirewall and spamfirewallmaintenance to match your mysql users prefs, spam thresholds, and expire times.
Add spamfirewall to your MTAs filter script. An example filter.sh is included.
Add spamfirewallmaintenance to cron. For example the following /etc/crontab line to run once an hour:
09 */1 * * * root /usr/local/bin/spamfirewallmaintenance >/dev/null
Main features:
- - Automatically queues the IP addresses of mail servers and spammers from messages
- that match the spam rules.
- Automatically firewall those mailservers and spammers if they send enough spam to meet your desired threshold.
- Automatically removes IP addresses from the queue and from the blocked list after a specified expiration period.
- Each repeat offense from a spammer will increase the amount of time they are blocked. With good behavior the amount of time will decrease.

old is a short from Open Lock Daemon and is a simple lock server which provides central point where to lock resources in a distributed environment by using TCP/IP to communicate with its clients.
Objects are identified by strings, so its really a general purpose server: you can use it to lock from files to pointers, as long as all your apps have a coherent object naming scheme. This makes it useful to any kind of distributed applications, for instance mailservers or databases.
It provides the basic locking primitives (lock, unlock and trylock) and uses a lightweight and simple network protocol, but there are both C and Python libraries which abstract you from handling it directly and provide the normal straightforward functions to use in a very simple and easy way.
Its written in plain C and has no dependencies on external libraries, and it has a decent performance (about 7850 lock(A); unlock(A) operations per second on a normal Pentium 4 2.8Ghz).
If youre intrested in performance, some measurements have been included inside the package, and you can find a small document in doc/performance (raw data files and scripts used are in doc/perf/ directory); but there are some not included in the tarball, let me know if you want them.
Enhancements:
- A very difficult to hit race was fixed, the library now compiles under Windows, and some minor code improvements were made.