First of I didn't ask postfix to do NIS lookups. These warning messages started showing up when I commented out alias_maps and decided to only use alias_database instead. The fix was simple.

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I used to receive around 5,000-7,000 spams daily on angsuman [at] taragana [dot] com email which is publicly available on the internet. It was consuming too many productive hours daily to fight spam. I decided to fight back. To reduce the spams I first made changes to my postfix configuration with the aim to stop most spams upfront. With 6 simple changes to my postfix configuration my spams dropped from 5,000 - 7,000 to a manageable 5-20 spams daily, often less. Let's look at these 6 simple postfix changes in details to drastically reduce your spam count too. I am consistently getting over 99% spam reduction after implementing these changes.

The changes proved to be safe and without false positives. In several weeks of manual browsing through the log file, I couldn't spot a single false positive (a case where legitimate mail is rejected).

Note: This changes do not involve (nor do they conflict with) spamassasin or clamav, which I might add later.
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I finally grew tired of email spams, having to delete several thousand spams a day while fishing out for valid emails is no fun. Occasionally I deleted valid emails too in the process. I realized I was wasting valuable productive hours dealing with junk from cretins and morons (aka spammers). I decided to fight back.

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Postfix is an excellent and powerful mail transfer agent (MTA) like sendmail. You can configure postfix to send outbound mails directly (default) or relay it to another MTA, which could be postfix or sendmail. However you don't want anyone to be able to relay mails through the server. So normally MTA's are configured to relay mails from trusted and/or authenticated networks only (configurable). Another option is available when your local MTA has a fixed IP address. However for all other cases using SASL is a very secure and easily configurable option as detailed below.

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I solve this problem in a different way. Normally we write rules to send messages to a particular folder. In that rule I set one of the action as to also forward the email. Remember to use one of the email accounts for specifying your rule, otherwise your forwarding will fail. Read the details on forwarding emails in Thunderbird here.

I faced a vexing problem with the otherwise excellent Mozilla Thunderbird email client. I was unable to forward emails to another account using the rules in Message Filters. I can normally forward emails. I can also execute other actions in the message filters except forwarding. It fails with a simple error message: "Sending of message failed". The simple solution lies in understanding the design of email accounts & message filters in Thunderbird, as described below in details.

BTW: At one point before solving this problem I even thought about switching to Evolution. And I am not alone. Several people posted the same problem on Mozilla forum without getting any solution.
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eBox platform provides a mini-debian installation along with its modules to allow you to provide and manage network services on your corporate network. The key capabilities includes support for multiple external network interfaces with load balancing, traffic shaping, transparent proxy, firewall, content filters, DNS (domain name server), NTP (time server), mail server, Jabber Instant Messaging server, SAMBA for file sharing, DHCP and more. In short it promise to be a one-stop solution for all network services needs for small businesses. Particularly I was interested in load balancing between multiple ADSL providers and traffic shaping capabilities. Here are my experiences with eBox platform.

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