For my fun project gibbon’s five, we’re using Google Apps to manage our emails etc. The other day I sent an email to one of our mailing lists and got a response that confused me at first:
Delivery to the following recipient failed permanently: $$$@gibbonsfive.de Technical details of permanent failure: Message rejected by Google Groups. Please visit http://mail.google.com/support/bin/answer.py?hl=en&answer=188131 to review our Bulk Email Senders Guidelines. ----- Original message ----- ... Received-SPF: softfail (google.com: domain of transitioning email@example.com does not designate 18.104.22.168 as permitted sender) client-ip=22.214.171.124; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning firstname.lastname@example.org does not designate 126.96.36.199 as permitted sender) email@example.com ...
So Google refused to deliver my emails to one of my mailing lists with an spf softfail? Why is this happening now and didn’t happen before even though I probably send 1321323 messages to that list?
I still have no clue why it never happened before, but if this is happening to you as well, the solution is quite easy:
You have to add your own mailserver – which I used to send the emails – to the TXT record:
@ IN TXT "v=spf1 ip4:188.8.131.52 include:_spf.google.com ~all"
If you have multiple mailservers, you can easily add multiple ip4 or ip6 parts