E-mail send from my own e-mail (example@domain.nl) to a Gmail-account is marked as spam. When I view the e-mail headers you will see a softfail. I have tried to set the SPF-record for my domain, but I keep getting a softfail: 
  

    Received-SPF: softfail (google.com: domain of transitioning example@domain.nl does not designate 2a02:348:83:cc40::1 as permitted sender) client-ip=2a02:348:83:cc40::1;
*2a02:348:83:cc40::1 = 141.138.204.64*

I have tried to set different SPF-records for the domainname: example.nl, an example: 

    v=spf1 ip4:141.138.204.64 ~all

What SPF-record to I need to set in order to 'pass' for the SPF? 

**Answer**

After reading more on Serverfault I've found the answer [here][2] and I used the following SPF:

    "v=spf1 a mx ip4:XX.XX.X.XX ip6:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX ~all"

  [1]: http://mxtoolbox.com/Public/Tools/EmailHeaders.aspx?huid=9ca01f9d-6257-4837-8dcf-2c9b3feb47d5 "MX Toolbox"
  [2]: http://stackoverflow.com/questions/19142369/create-both-ipv4-and-ipv6-spf-record