Hey @Konstantin, I think a valid Yandex configuration (once you’ve enabled SMTP as described in their docs) would look like so:
N8N_EMAIL_MODE=smtp
N8N_SMTP_HOST=smtp.yandex.com
N8N_SMTP_PORT=465
[email protected]
N8N_SMTP_PASS=myAppPassword
[email protected]
N8N_SMTP_SSL=true
That said, when I tried this, Yandex’ SMTP server rejected the invitations sent by n8n:
2022-05-25T09:03:12.051Z | error | Failed to send email {"recipients":"[email protected]","error":{"code":"EMESSAGE","response":"554 5.7.1 Message rejected under suspicion of SPAM; https://ya.cc/1IrBc 1653469390-HJ9Eb4DLIS-3AKC8sjP","responseCode":554,"command":"DATA"},"file":"NodeMailer.js","function":"sendMail"}
This response “Message rejected under suspicion of SPAM” is coming from Yandex and I don’t think this problem could be addressed from n8n’s end unfortunately. Yandex simply doesn’t seem to like automated messages 
So you might want to consider an alternative email provider for use with n8n or manually accept new users without an email being sent as suggested here: [User Management] How to invite users with SSL-less/unauthenticated SMTP server? - Questions - n8n