If you run DNS and SMTP servers, you probably know how important it is to validate the configurations used by your SMTP relays and DNS servers. Broken configurations can lead to clients not being able to find your website, open mail relays, unroutable mail, and your domain being blackholed by the Internet. Luckily there are three awesome services that can be used to sanity check the DNS and SMTP servers for a domain. The first service is the Mail abuse website, which checks to see if your mail server is acting as an open relay:
The second service is DNS report, which validates the DNS server configuration for a specific domain:
The last service is the open SPF website, which allows you to generate SPF (Sender Policy Framework) TXT records for a domain:
I use all three services, and can’t begin to describe how useful they are.