What is the meaning of the SMTP error "451 4.7.0 SPF tempfail: DNS timeout"


We are receiving this error on mails mails send to one specific domain.
Mails are not delivered. When I remove the SPF record I don't get an error message and I am currently waiting for a reply from the recipient. I sent the email using telnet so there is no way of tracing the message.

But I can not leave our domain without SPF record. So I need to figure out what is happening.

Thanks for any help.

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BrainSolutionsAuthor Commented:
Hello all,

I found the problem and the solution. My SPF record was not sufficient as it missed a host in the domain for which the spf record served.

It workes normally now.

BrainSolutionsAuthor Commented:
An SPF record that covers multiple domains shoud contain A pointers to hosts within all the domains
Actually that isn't completely accurate.

All the SPF record needs is the sending IP(s) for that domain.  If your domain is example.com, and your sending servers are and, then your SPF record would be:
"v=spf1 ip4: ip4: -all"

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If you are DKIM signing, which you should be, then I suggest changing -all to ~all

If you want to post your SPF record, I can double check it for best practices and such.
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