Deliverability Tools

In no particular order

https://emailstuff.org/spf/check	https://viewdns.info	https://toolbox.googleapps.com/apps/messageheader/
https://www.kitterman.com/spf/validate.html	https://www.diggui.com	https://mha.azurewebsites.net
	https://www.whatsmydns.net