diff --git a/app/models/user.rb b/app/models/user.rb
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -19,7 +19,7 @@
   belongs_to :site
   belongs_to :country
 
-  named_scope :activated, :conditions => {:activated => true}
+  named_scope :activated_users, :conditions => {:activated => true}
 
   validates_presence_of :login
   validates_uniqueness_of :login
@@ -36,6 +36,7 @@
   validates_format_of :email, :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i, :allow_blank => true
 
   validate :uniqueness_of_email_from_activated_users
+  validate :enough_time_interval_between_same_email_registrations
 
   attr_accessor :password
 
@@ -87,6 +88,9 @@
   end
 
   def activation_key
+    if self.hashed_password==nil
+      encrypt_new_password
+    end
     Digest::SHA1.hexdigest(self.hashed_password)[0..7]
   end
 
@@ -117,8 +121,18 @@
     end
 
     def uniqueness_of_email_from_activated_users
-      if User.activated.find_by_email(self.email)!=nil
+      user = User.activated_users.find_by_email(self.email)
+      if user and (user.login != self.login)
         self.errors.add_to_base("Email has already been taken")
       end
     end
+    
+    def enough_time_interval_between_same_email_registrations
+      open_user = User.find_by_email(self.email,
+                                     :order => 'created_at DESC')
+      if open_user and open_user.created_at and 
+          (open_user.created_at > Time.now.gmtime - 5.minutes)
+        self.errors.add_to_base("There are already unactivated registrations with this e-mail address (please wait for 5 minutes)")
+      end
+    end
 end