Shopify built the software.  Cannot speak to a human, so stuck asking here.  I have clicked all around the store to try and find a way to tell the software to stop recommending.  No place to do this.  Thus my request for advice.  Thanks

My store is located in Arizona.  We have a resale license for AZ and pay the taxes on the products sold.  Our accountant is located in another state, TN.  Because of that address being in TN, we constantly get told by the software to add TN for taxes...

Shopify takes a lot of money from my sales, I would prefer to use the system they have.  Mailchimp would cost a ton more. 

I have 18,000 customers/subscribers on my store and Shopify is blocking my email blast.  I have tried twice and both get 5% out and then "Fail."  It said I paid for every 1,000 over 10,000.  What gives?