I send email but the email is not coming

When I log in to Roundcube, I can send e-mails, but I cannot receive e-mails to the domain e-mail address I created. Why is this happening? Some people said to use Yandex mail or Gmail but I couldn't find the place to use it in CWP. How can I do this?

Do you have a resolvable FQDN A record and working reverse DNS (PTR) provided by your hosting company? These are critical to ensure mail delivery. What is the IP address of the server so we can test its DNS setup?