olemus
saadetise blokeerimine SPF-funktsiooniga

ülevaateid
https://help.returnpath.com/hc/en-us/articles/220226488-Troubleshooting-Sender-Policy-Framework-SPF-failures

https://www.dmarcanalyzer.com/spf-failure-mean/

https://knowledge.ondmarc.redsift.com/en/articles/1148885-spf-hard-fail-vs-spf-soft-fail

https://www.duocircle.com/resources/how-to-fix-spf-records