Mailchimp and SPF records

I maintain the monthly newsletter from our local chapter. To make life a bit easier I use Mailchimp (free version) for this purpose.
That is what they exist for ;-). But noticed that it didn’t received the newsletter anymore on my mail address. Fyi ON4AOB is the callsign from our club. But I had no clue what was going on. I started by disabling the spam filter, no result. I added myself with a second email to the list. This worked. So the problem seems to be with the on4aob domain. In Mailchimp I didn’t found bounces or any other error records, so little to investigate on.

Few days go by without any solution. At work, adding a partners mail server to our DNS records opened my eyes. I had never added Mailchimp to our DNS records.
This lead to marking all mails form Mailchimp sent with an address as possible spam and not delivering them.

The solution was adding the needed SPF record. Head over to to find out what they are. In short : it allows a third party to send mails on your behalf.

My basic record was :

v=spf1 mx a -all

This will translates as :

  • version 1 (SPF1)
  • allow my MX record (Mail eXchanger)
  • my own A record (ip of my hosting server)
  • (this is my hoster).
  • -all hard fail, block all mail not authorized by this record

There was the problem, I never authorized Mailchimp on my side. Reworked the entire SPF record and waited to see what happens when the newsletter from december is mailed.

New SPF record :

v=spf1 mx a ~all

So, is now included and I changed the fail from hard fail (-all) to soft fail (~all).
And yes it works!

Tools to check (your) record: