Checking domain names, IP, etc can be a burdening task and I'm wondering who uses what.
Here are a few helpful tools I've found:
still in beta, but handy for those domain names and IP's it does recognize
the old whois.sc search
Nice dossier and other tools
various assorted tools
swiss army knife internet tool
provide a range of tools that are useful to senders and recipients of email
MX records / services
MX lookup is done directly against the domain's authoritative name server, so changes to MX Records should show up instantly. You can click Diagnostics, which will connect to the mail server, verify reverse DNS records, perform a simple Open Relay check and measure response time performance. You may also check each MX record (IP Address) against 147 DNS based blacklists. (Commonly called RBLs, DNSBLs)
Spam Reporting Addresses
the anti-spam portal: everything you didn't want to have to know about spam. Whether you are entirely new to the struggle against spam, or are a seasoned professional system administrator, we direct you to the best resources available to counter spam.
Newly Registered Domain Name Lists