DNS troubleshooting
- http://www.dnsinspect.com/ **** great info to get
- http://www.intodns.com/ check your DNS settings
- http://viewdns.info/ good info can do a domain DNS record listing
- http://www.dnsqueries.com/en/
- https://check-host.net/ check your host from various countries
- https://www.ipvoid.com/ IP Address Tools Online
SPF check
- http://www.kitterman.com/spf/validate.html
- SPF check from Mimecast
- Generate spf record wizard
- check dkim https://www.dmarcanalyzer.com/dkim/dkim-checker/
- https://www.mail-tester.com/spf-dkim-check
Blacklist removal
Free Public DNS servers
Setup Secure DNS