Defensive Security Handbook, 2nd Edition

Chapter 23. The Extra Mile

Congratulations! You’ve made it to the last chapter! Here’s a cookie:

document.cookie = "username=LastChapter; expires=OnReceipt 12:00:00 UTC";

After reading this book, you should be ready to provide the sound building blocks of an information security program. You should also be fully equipped to handle the common insecure practices that we’ve seen in so many environments. But the learning doesn’t stop here! Here, in the extra mile, we’ll give you some additional tidbits of information and some great resources for you to go check out that will make your defenses that much stronger.

Email Servers

Running and installing an email server is a large time and technology commitment. Bulk spam and phishing are major concerns. Modern spam filters claim to block 99.99% of spam and phishing emails, but to give you an idea of the scale of the problem, it is estimated that nearly half of all emails sent worldwide are spam.

You’ll also need to watch out for commonly misconfigured server settings. Many email servers currently on the internet are misconfigured, which contributes in part to the amount of spam being sent. In addition, misconfigurations may delay or even prevent an organization’s mail from being delivered—certain configurations will land the IP address or domain of the mail server on a block list, which organizations can subscribe to for enhancing filtering efforts. There are some common configuration checks that should be performed on mail servers being ...