I've replied to this thread several times and finally just ignore what tech support was telling me, because I tried it ALL.

Recently I tried something that no one ever suggested and that was to send emails from my QB email. Firstly, I never knew I even had QuickBooks email and stumbled onto that option when messing around in my preferences. Instead of connecting my gmail, or hotmail, I clicked on that option. I haven't had any problems sending bills since. I don't know how this fixed the problem, I don't know how I exactly did it, but it did. However, I don't think QB email is the same across all QB users. I wish I could guide ya'll through the process but basically I was just so frustrated I figures screw it I will try just about anything, because otherwise I was going to leave QuickBooks merchant account entirely. No point in paying for a service I can't use.

I'm running QB accountant desktop for PC 2023.