Discuss SPF: Is adding ip4 127.0.0.1 a bad idea? in the DNS forum on Dev Shed. SPF: Is adding ip4 127.0.0.1 a bad idea? DNS forum discussing issues, servers, and configurations. The Domain Name System (DNS) is what the Internet uses to translate website names into IP addresses.
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SPF: Is adding ip4 127.0.0.1 a bad idea?
I just wanted to clarify something in my mind (since I cannot find a decent example on the net) regarding SPF and the use of a localhost/127.0.0.1 address.
Basically I have a problem where an SPF record has been created for a website pointing to the public IP address of the mail server and its associated A and MX records.
However since this website runs from a PHP mailer function where the shared hosting is configured to point its SMTP to 127.0.0.1 the SPF record reports mail (which is valid) as spam since 127.0.0.1 appears on the mail headers but does not appear in the SPF record as a valid sender.
Now my understanding is that it would be a very, very bad idea to add 127.0.0.1 as a valid sender in the SPF record because then anyone could send PHP mail to their own local 127.0.0.1 address and it would fool the SPF record into thinking it is valid.
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Shouldn't really be an issue having it in there. When a receiving server checks for an SPF record, it looks only at the IP it received the message from. Not the IP's prior. This is why SmartHost or forwarding services can cause SPF woes. If you need to add it to get around a current config, theoretically it shouldn't cause an issue. However if other people have a similar set up where a message is accepted and then passed off to another server and shows it came from 127.0.0.1 by the time the SPF check happens, it would essentially be useless. But how likely/common would that be...? If you have no way to change your internal config and must add it, I don't think you'd have much fallout from it. Plus there aren't too many servers that even check SPF records unfortunately.