Useful Tools
Pasteboard
http://pasteboard.co/Pasteboard is a quick and simple image sharing web app driven and developed by Joel Besada.
Images uploaded to Pasteboard are publicly available but not broadcasted, meaning it is up to you to decide who you share the images with.
Kitterman SPF Record Testing Tools
http://www.kitterman.com/spf/validate.htmlThese tools are meant to help you deploy SPF records for your domain. They use an actual RFC 7208 compliant library (pyspf) for tests and will dynamically test for processing limit errors (no other testers I'm aware of do this). This site uses a caching DNS resolver, so for tests that use live DNS, results will be cached for the Time To Live of the DNS record. For most basic uses, these tests should be reasonably self-explanatory. Advanced users may need, and probably want, some additional information on how these tools work. It can be found here.
MX Lookup Tool - MXToolBox
https://mxtoolbox.com/MX Lookup will list MX records for a domain in priority order. The 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 105 DNS based blacklists. (Commonly called RBLs, DNSBLs)