DNS and IP Lookup
I use Sam Spade predominately for its IP address lookup and DNS reverse lookup features. In the tool suite, right-click an FQDN or enter it into the main field, then click the Whois tool. Sam Spade returns reverse DNS lookup information from one of a variety of Whois sites. The tool bundle also includes the DNS lookup tools Dig and Nslookup.
Sam Spade color-codes its output, letting you easily scan for relevant information, such as organization name and host country. The tool also gives you information about a net-block (a block of consecutive IP addresses, aka a subnet) so that you can see whether the ISP is, for example, a large provider for a DSL or cable service or a provider for a single company. In addition, Sam Spade includes a rudimentary port scanner, an SMTP relay test tool, a blackhole lookup tool, and a Web site fetching tool similar to Wget.
On the Case
Sam Spade lets you easily run multiple commands to look for different pieces of information and further analyze the results by using the tool's context-aware menus. You can even configure the suite's logging to save all the interesting information you find during your investigations and copy it to another program or write it to a text file. Although spam, phishing, and other email threats continue to grow, you probably won't analyze even a fraction of the total email you receive. But when you do need to investigate a suspicious email message, Sam Spade is on the case.