Another business owner jumping in.  How broke d*ck is your support because not being able to:

1.  Send anything via email (fyi text or messenger isn't how most businesses send POs, Estimates, and Invoices).

2.  Not receiving confimation if an email is screened out.

is complete BS. 

1.  Get Sendgrid on the phone, have them arrange not restriction for your IPs.  Not rocket science.

2.  Work with Mail chimp, SendGrid, and the bot lists to penalize those who are spamming not just hammering everyone.