Why do letters from the site that come to Gmail end up in spam?

Question

gmail

Good afternoon, I created a corporate mail for the site on mail.ru (mail for business section) of the type [email protected] MX-records, SPF-record and DKIM signature are configured correctly, from personal account mail screen prntscr.com/gho1wt
Hosting also confirmed the correctness of the settings, Yandex
Screen from mail-tester.com https://prnt.sc/gggo72
With other mail services emails go to inbox but gmail goes to spam

Answer 1

There can be many reasons. But you need to start by properly setting up your mail server (or choose a good third-party service that will take care of itself, such as mailgun or mailchimp).
The most basic things that should be this:
SPF-record - a registry of servers that will send mail from your address, so the recipient will know that you (or your server) sent the sender, and not someone else sent from his server.
DKIM signatures are a specially designed digital signature format to protect against spam mailings, again, its purpose is to fight false senders, so that the spammer does not pretend to be someone else (roughly speaking).
These are the two basic things that will minimize the chance of a letter getting into spam with a primary neutral/white reputation for services like mail.ru/gmail and so on. And then other factors begin to play a role: how often the recipients themselves send your letters to spam, the content of the mailings, the presence of an unsubscribe button (this is primarily true for identical letters sent to thousands of recipients), and so on and so forth.