In order to reduce the likelihood of emails from your domain falling into spam, you need to set up a digital DKIM signature for your domain.
In the hosting control panel, go to the mail settings and enable this option, as shown in the screenshot below.
If the domain is delegated to other DNS servers, add a TXT record as shown in the example.
When sending a letter, a signature will be added to the header, which will be verified by the recipient server through the DNS record, which will be a confirmation of sending letters from this domain.
In popular mail services, this would look like this:
If the signature field matches the domain name, then everything is configured correctly. Such letters are considered more reliable by mail servers and the probability of falling into spam is reduced.