To unlock iCloud account

I never heard of unlocking Apple ID's by sending emails to it, a quick google did not give me more intel either... Are you sure this is not a scam? See this link about locked apple ids as reference

If your Apple ID is locked or disabled - Apple Support (CA)

Contact Apple ID Support for assistance.  See the Apple Support articles below for contact information.  

Apple ID - Official Apple Support.   -

Contact Apple for help with Apple ID account security - Apple Support.  *   (Link doesn’t always load)  

Get Support      -    Work through the screens to get a chat option. You may have to pick a slightly different problem.

Apple Support schedule phone call.   -

Apple on Twitter       

From the Apple Support article below. 

Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.

Security and your Apple ID - Apple Support.      *

See if you can get a Rescue or Notification email option.

See if anything in Section 3 helps.

Apple ID - Password/Security Questions verification e-mail not received.   *