How to get rid of getting emails sent from your server to spam?

Question

Email

We moved the site to a new server at DigitalOcean, there is plesk, everything is set up for mail as much as possible, but apparently this is not enough, now we were spending blackfriday in the online store and there were a lot of undelivered letters.
Apparently a response to the increased flow of incoming letters (there are notifications like - your new order, change in order status, etc.)

What should I do? To transport mail to Google? =(

Answer 1

Use amazon ses or sendpulse

Answer 2

The mail itself can be set up anywhere, Mile ru for business, Yandex Connect, two free and dimensionless options, Google Workspace or somewhere else.
But I recommend setting up sending emails from the site via third-party SMTP. There is a choice, but I recommend trying via smtp bz

Answer 3

https://www.mail-tester.com/
but better, of course, with services