If you meet the trouble like link2seed you need to send a test mail via Stuido->Dashboard->server audit area. See the line with "Mail sending - click here to send test email". Click link, follow the instructions and check what result do you get. Provide us this part, then it's possible to start to check the variants what's wrong.
Hi, LeonidS! In accordance with your recommendation, I have tried to send a test email. UNA returns a message like "Sending mail - a test message has been sent, please check firstname.lastname@example.org box" (has been translated from Russian). I have no email messages from my site in 1 hour (also in the spam folder). So could you clarify please, what I need to check in this case?