Mail, Google Apps, Cpanel, and SPF

Sender Policy Framework (or SPF) is an email validation system designed to addressing source address spoofing. It allows administrators to specify which hosts are allowed to send email from a given domain by creating a specific DNS SPF record in the public DNS. Mail exchangers can then check that mail from a given domain is being sent by a host sanctioned by that domains administrators.

So, after setting up mail from Google apps you’re getting this error:
(IP addresses and domains have been changed to protect the innocent)

SMTP error from remote mail server after RCPT TO:<>:
host []: 550 <>:
Recipient address rejected: undeliverable address:
host[] said: [] is currently not permitted to relay 550-through this server. Perhaps you have not logged into the pop/imap server 550-in the last 30 minutes or do not have SMTP Authentication turned on in your 550 email client. (in reply to RCPT TO command)

You check your DNS records and everything seems to be in order…
You’ve changed your cname for mail to point to Google:
You’ve changed your MX records for your domain to point to Googles: etc
You’ve configured your server in Cpanel to act as a Remote Mail Exchanger

For Google to accept your mail server as a relay, you need to enter a line in your DNS zone: TXT v=spf1 ~all
(Do not use the built in SPF in Cpanel, and you may need your host to enter this line for you)

A little info is here for Google Support
Background reading in SPF in Wikipedia is here

5 thoughts on “Mail, Google Apps, Cpanel, and SPF”

  1. Sorry for the delay…

    OK the difference is quite minor but important:
    ~all evaluates all mail as neutral, whereas -all will cause a hard fail.

    The reason Google has this in the KB/Wiki is that not everyone uses Googles own SMTP servers to send outbound email and using -all would cause problems in this situation causing email to be marked as “Fail”.

    SPF Framework is covered here

  2. Thanks for explaining the difference between ~all and -all.

    That one has been bugging me for quite a while

  3. Thanks for clearing up that difference I asked about in June.

    its only taken me six months to come back 🙂

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