Why don't letters from smtp.gmail.com come to yandex mail?

Question

Yii

The service uses registration confirmation via mail, the mail account is configured for gmail, recently I often encounter the problem that the letter does not come to customers with yandex mail.
The most interesting thing is that the letter was sent in the mailbox.
Someone faced such a problem?

Answer 1

There was a problem that Gmail did not allow sending from undefined devices. Actually, it was only required to put a tick on allow in gmail itself.
Well, it would be nice to see the settings, not the logins themselves, but SSL in general. Himself literally a day ago made a confirmation on the soap box. I sent to Yandex, everything was in order.