ruby on rails - Devise not respecting config.email_regexp -

I wanted to change the regex defining a valid email in my application. I'm trying to do it in config / initializers / devise.rb. To check whether regex was working, I tried

  config.email_regexp = / \ d + /   
 when that does not work I thought that my knowledge of Ruby's reggae sytax had stopped and what I thought was a super simple reggae  
  config.email_regexp = / a /   
 While making changes in the following, there is no effect on password permission, so there is no effect in the previous two rows.  
  config.password_length = 2..128   
 What else should I do to modify the valid email regex? (After each of these modifications I restarted the server to ensure that the changes were made.)   
 
 
 Do you know the Reggae match is correct?  
 / \ d + matches one or more digits, and / a / matches a single 'A', this almost every email address will be invalid, will not it?  
 To test your regexes, look at this site and see if it helps: