SPF – Dmarc report

I get Dmarc reports sent from various different sources. All of the reports generally have <result>pass</result> for all of the sections.

However, the reports from Google always have SPF fails:

<row>     <source_ip></source_ip>     <count>1</count>     <policy_evaluated>         <disposition>none</disposition>         <dkim>pass</dkim>         <spf>fail</spf>     </policy_evaluated> </row> . . . </auth_results>      <dkim>         <domain>domain.co.uk</domain>         <result>pass</result>         <selector>dkim</selector>     </dkim>     <dkim>         <domain>email-od.com</domain>         <result>pass</result>         <selector>dkim</selector>     </dkim>     <spf>         <domain>bounce.domain.co.uk</domain>         <result>fail</result>     </spf> </auth_results> 

My SPF record looks like:

“v=spf1 +a +mx +a:server.domain.co.uk include:email-od.com ~all”

I am unsure why my bounce domain is failing SPF checks, but it only seems to be on Google DMARC reports.

To be honest, I am unsure what the bounce domain does, should I set up an email address – bounce@bounce.eazyfreight.co.uk?

Any help sorting my SPF and advice re bounce.domain.co.uk would be great.