: Spam being sent from my domain I have a suspicion that somebody is sending spam from my domain. Today I received an email from postmaster(AT)halliburton.com to htuwxjw(AT)example.com which said:

@Ann8826881

The ideal way to do this is to send a hard fail on email that isn't coming from your server IP address or your specified MX record by doing this:

v=spf1 +a +mx -all


This however will not stop the email from being sent. Spam filters do various checks on an email that has been sent out, one of them will be a check on the SPF record of the domain it is supposed to have come from and compare this to the IP address/MX record this has come from. This is one way to prevent and help disavow people sending emails pretending to be you but it will not put a complete stop to it. In a way this will make sure that the your domain is safe. Normally however it is the IP address that it is sent from that gets blacklisted.

Just a quick addition. You would probably be better using

v=spf1 +a +mx ~all



- is a hard fail and may cause delivery problems
~ is a soft fail which shouldn't cause delivery issues (in case of a false positive however this is very low risk)
if you do get stuck you could always try a wizard to do this for you. Try here
Hard Fail is recommended as it will turn away all that do not match where as a soft fail will just flag the mail and let it through
+mx and +a is the same as using just a and mx


I personally do use the hard fail but some people do experience issues with this.

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