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Does the receiver check SPF ??

Posted: Thu Oct 25, 2007 3:21 am
by gzox
Dear,

I must check for few email servers (not my servers) does they check SPF of incoming emails when they receive. They usually have defined their own SPF, by I do not know does they check SPF of incoming emails when they are receiving.

It will be very helpful if you know some online internet service for it to check. I will be very thankful to you.

Also it is very important to me if I could check, with my PHP script, does the some domain have defined SPF? Do know something about that?

Posted: Thu Oct 25, 2007 3:34 am
by Chris Corbyn
Not all receivers check the SPF, but most MX servers with spam checkers will run a SPF check yes.

To check SPF records all you need to do is run a DNS query for a TXT record which starts with "v=spf1". There's a tool called 'dig' which allows DNS queries to be made:

Code: Select all

w3style:~ d11wtq$ dig TXT gmail.com

; <<>> DiG 9.3.4 <<>> TXT gmail.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20585
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 0

;; QUESTION SECTION:
;gmail.com.                     IN      TXT

;; ANSWER SECTION:
gmail.com.              300     IN      TXT     "v=spf1 redirect=_spf.google.com"

;; AUTHORITY SECTION:
gmail.com.              345600  IN      NS      ns4.google.com.
gmail.com.              345600  IN      NS      ns1.google.com.
gmail.com.              345600  IN      NS      ns2.google.com.
gmail.com.              345600  IN      NS      ns3.google.com.

;; Query time: 265 msec
;; SERVER: 192.168.1.1#53(192.168.1.1)
;; WHEN: Thu Oct 25 18:35:02 2007
;; MSG SIZE  rcvd: 150

w3style:~ d11wtq$

Posted: Thu Oct 25, 2007 8:54 am
by gzox
Thank you Chris.

I am sorry, I am not understand all things about servers and spf. (What types of mail servers exists and with which tipe(s) we communicate when we send a message.) I want to ask:

Is the SPF only in relation with mx server? And, do we communicate with MX server only when we send message directly without of smtp server?
I mean: If I send message with my smtp server (not dierectly send to mx server), could then receiver block my message (using the SPF)?