Why is the message blocked due to SPF?

If an email has been rejected due to SPF (sender policy framework) this is because the sender is sending from a location that is not in the SPF record of the sending domain. An SPF record outlines the host names and IP addresses that the sender can send from. Eg:

 

smxemail.com txt
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14458
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;smxemail.com. IN TXT

;; ANSWER SECTION:
smxemail.com. 7200 IN TXT "v=spf1 include:spf.nz.smxemail.com -all"

If the SPF record is set to hard fail (-all at the end of the record) and the email is coming from a location which is not in the SPF record then the SMX platform will reject the message with a bounce-back to senders mail server.

You can see the IP address that sender is sending from in the SMX Email Admin Portal by double clicking on the message in the search results and looking at the “From Host:”

 

Kitterman is a good website where you can check the current SPF record for a domain and also check a proposed SPF record you plan to add or update for a domain.

 

If an email is rejected due to SPF it is best for the senders IT support update the SPF record or send from a location already in the SPF record rather than adding a whitelist in the SMX email admin portal. Whitelisting can cause security risks and is only designed to be a temporary solution.