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 @on4aob.be 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 @on4aob.be address as possible spam and not delivering them.

The solution was adding the needed SPF record. Head over to Postmarkapp.com 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 include:webawere.nl -all

This will translates as :

  • version 1 (SPF1)
  • allow my MX record (Mail eXchanger)
  • my own A record (ip of my hosting server)
  • Webaware.nl (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 include:servers.mcsv.net include:webawere.nl ?all

So, servers.mscv.net 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:

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