MXAlerts
MXAlerts performs 24/7 remote round-trip email server monitoring software. We confirm email can be sent and received from your email server or exchange server.
MxToolBox
Monitors the performance of your websites, DNS, and email servers along with blacklist monitoring. Get alerts by e-mail and SM ...
SPF Toolbox
SPFtoolbox is an Open Source Javascript and PHP app to look up DNS records such as SPF, MX, Whois, and more