MxToolBox - All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.
ManageEngine Mobile Device Manager Plus - ManageEngine Mobile Device Manager Plus is an enterprise mobile device management solution that is designed to enhance employee productivity without compromising on corporate security.
Dnsstuff - DNSstuff offers DNS tools, Network tools, Email tools, DNS reporting and IP information gathering.
Scalefusion - Scalefusion is a Powerful Android, iOS, macOS & Windows 10 Device Management Solution for corporate-owned & employee-owned (BYOD) mobile, tablets, desktop & rugged devices.
SPF Toolbox - SPFtoolbox is a Javascript and PHP app to look up DNS records such as SPF, MX, Whois, and more
Jamf Pro - Jamf Pro is comprehensive enterprise management software for the Apple platform, simplifying IT management for Mac, iPad, iPhone and Apple TV.