Does this user receive ANY emails?
If not, check your Admin Tools configuration. If you have entered specific email addresses to be sent the Admin Tools emails which do not include the email address of this user (exactly as entered in this user's Joomla user profile) then it makes sense that this user does not receive the email; that'd be exactly what you configured.
Remember that the rescue information IS NOT SENT TO THE USER THAT FAILED TO LOG IN. The rescue information is part of the IP block email sent to the email addresses of super users configured to receive these emails in Admin Tools' backend options. The very simple reason is that since the login failed we don't know if that request comes from a legitimate user or an attacker. Right?
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!