SPF Record Verification
Assuming you have already created your SPF rule, added it to your DNS, and want to check your SPF configuration. The SPF record is stored in DNS as TXT and you can manually check the SPF record for a domain by using nslookup or dig as follows
1. In the terminal type
nslookup -type=txt yourDomain
dig txt yourDomain
Replace yourDomain with your domain name, for example,
nslookup -type=txt example.com,
2. If an SPF record exists, the result would contain your record starting with
3. If an SPF record doesn’t exist or there is a problem retrieving the record for the domain there would be no
v=spf1 property in the output.
To test your SPF, you can also check if the DNS entry for your SPF is correct by entering your domain into https://mxtoolbox.com/spf.aspx. If you set your DNS entry correctly it will show you the results meaning your SPF passed the test. The mxtoolbox should be enough to test your SPF but there other tools available online for this purpose. For example, another tool you can use to see a list of IPs you set as authorized in your SPF rule is http://tools.wordtothewise.com/spf. To check the DNS entry for your SPF you can also use http://www.kitterman.com/spf/validate.html.
You can also send an email to Gmail and to see if your email shows mailed-by on the email information, which means your email SPF configuration has been successfully recognized by Google.