My emails are constantly going into my client's spam folders

• I use gmail as an email client for my website's emails.  No forwarding.
• I have used the email authentication tool and set SPF, DKIM and DMARC (including a reject/quarantine policy)
• Some of my email recipients have me in their address books and some of the emails that are being sent to spam are replies that I am sending to emails that they are sending to me.  (So whitelisting cannot be the answer.)
• I have checked all blacklists and my site is not listed in any of them.

I have run MXtoolbox the ONLY errors I get are those shown below.

I quite literally cannot do business like this. What more do I need to do to even send a simple email with confidence that my client will receive it?  There is nothing more the client can do from their end.  I'm already in their address book.  There should be no reason for my emails to be going into junk.  

The fact that this is happening with the majority of my emails (and not a select few with possibly strict spam rules) means that the cause is most certainly on my end. 

Since I have taken all the steps that I possibly can and this still occurs means that the problem lies with Inmotion Hosting.