No emails from MyCloud system

I have new installed MyCloud EX2 Ultra. When I log in as admin using my local IP address I create new user but email messages do not reach the recipient and he can’t set his own password.
When user try to log in to and use option “Forgot password” and try to reset it, he gets information:
“An email was sent to user_name@gmail . com with further instructions on resetting your password.” but there is no email in his inbox (and SPAM folder too of course).
I tried a few emails on 3 different servers.

When that user try to log in to MyCloud . com it has information about incorrect password - probably because user can’t get his email with account info and Cloud devices code.

What can I do?