Is it possible to configure mail sending without MX records?

Question

PHP

I set up postfix on a test server centOS 7.
I'm testing the php code there.
And for the life of me, I can't send any mail with the mail() function. The
postfix logs say that the letter was sent, but does not come.
From this two questions:
1. Does anyone have a postfix setup manual on a test server? Not all codes are tested on production balalaikas.
2. Naked server, how to make php send emails. Google through the smtp bridge bans by ip, yandex does not give an answer at all.
The people, who organized this function in their own way ??

Answer 1

Take any ready-made smtp gateway (sendgrid - 12,000 emails per month for free, mailgun - 10,000 emails for free) and don't worry.

Answer 2

Gmail API

Answer 3

If there are a few letters, try ssmtp (CentOS definitely has it) configured to send through the same Yandex.
In postfix, client authorization (to Yandex or Google) is also present, but it is much more difficult for an inexperienced person to launch it

Answer 4

Thanks to all.
The issue was resolved by getting a free .tk zone domain
AND basic postfix settings