SysteMajik Consulting

Tag: spam

  • Detecting Email Server Forgery

    Most of the spam I received has been sent by servers forging or otherwise obscuring their server identity. RFC2505 states that the server identity and sender address are easily forged. Of these, it is easiest to identify server forgery. Very little, if any, of the personal email has a forged server identity. Unfortunately, legitimate bulk and automated email often show signs of server identity. If you deliver either of these types of emails, this article will provide information on fixing the situation.

    The rules here apply to emails originating from the Internet only. Mail User Agents submitting email are expected to violate these rules. MUAs should use an authenticated encrypted connection to the Submission port (576). Relay servers should not apply these rules to connections originating from the local network.

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  • Signing Return Path Addresses with Exim

    I have been receiving a fair amount of Spam from an e-mail forwarder. They are unwilling to correct their problems. Much of this Spam is in the form of bounce notifications. Attempting to reject other Spam resulted in more notifications. To control this Spam I implemented signed return path addresses. As a side benefit, I am also rejecting bogus notifications sent directly to me.

    Signing my return path allows me to reject faked notification e-mail. The SMTP standard requires that no email sent with a null return path “<>” (aka Envelope Sender) be returned. Its purpose is for allowing for notifications about existing messages. These include notifications such as address unknown, message delivered, and message read. E-mail notifications which are not about a previously sent message can be refused. Signing the return path allowed me to reject such invalid notifications.

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  • Running an Email Server

    I administer an email server for a couple of domains and a few users.  Incorrectly configured email servers result in a lot of my administration work.   Due to improper configuration, far too many servers look like Spam servers.   A little effort in setting up your server can make my life easier, and increase your chance of successfully delivering email everywhere.  This article describes steps you should take. (more…)