On Fri, Apr 15, 2016 at 10:56 PM, Tim <ignored_mailbox@yahoo.com.au> wrote:
Chris Murphy <lists@colorremedies.com>:
> FYI, gmail puts your emails in spam for the following reason:
> Why is this message in Spam? It has a from address in yahoo.com.au but
> has failed yahoo.com.au's required tests for authentication.

This is, unfortunately, a well-known issue between Google and Yahoo. We're on Google at work so I get to deal with this on a semi-regular basis. 

There is something called DMARC (you can Google for that term, the first few hits are directly relevant). Without going into all the details, suffice it to say that Google believes Yahoo has DMARC in place, but they're doing it wrong. This results in mail from Yahoo coming from servers that Google thinks it shouldn't be coming from, so it gets rejected, flagged as spam, etc.

I haven't researched it thoroughly enough to figure out who's right and who's wrong here, but the bottom line is that it is hard to receive mail from Yahoo users on Gmail.