If you or a client are not receiving email from the system, including registration invitation, even after checking spam/junk, the email provider is blocking it. Email from blinksession.com and login.blinksession.com needs to be white listed, which will tell the email provider to stop blocking it.
Whitelist email from blinksession.com and login.blinksession.com For Personal Email:
Gmail
Yahoo
Hotmail/Outlook
Whitelist email from blinksession.com and login.blinksession.com For Company Email Admins
Google Suite Gmail
Office 365