On Windows 7 (or Vista) I use
Mail Server Test (2015/10/28 15:49)
Mail Server Test is a tool for testing your mail server configuration and related DNS records. The tool checks your setup against large number of rules based on RFC standards and industry best practices for achieving high email delivery rates. Whether you run your own mail server or you use a third party mailing service, this tool will help you reveal potential problems with your email infrastructure.