Emails are failing

My Mautic version is: 4.4.6
My PHP version is:
My Database type and version is: PostgreSQL

My problem is:

I am using hostgator SMTP server, and I have 500 emails per hour, however I’m sending 40 per 5 minutes, that’s 480 per hour. They all land either in spam or promotions, not in inbox. Also, most of them are failing, simply not sending anything. My cron jobs are right and I have the correct DKIM, DMARC, SPF, MX etc configuration.

I can’t see the problem here. I’ll attach some photos if somebody has any idea.