MxToolBox - All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
Dnsstuff - DNSstuff offers DNS tools, Network tools, Email tools, DNS reporting and IP information gathering.
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
SPF Toolbox - SPFtoolbox is a Javascript and PHP app to look up DNS records such as SPF, MX, Whois, and more
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.