took out unnecessary wordage, changed "number" to "amount"

actionmailer/README.rdoc

@@ -119,8 +119,7 @@ trivial case like this:
   rails runner 'Mailman.receive(STDIN.read)'
 
 However, invoking Rails in the runner for each mail to be received is very resource intensive.  A single
-instance of Rails should be run within a daemon, if it is going to be utilized to process more than just
-a limited number of email.
+instance of Rails should be run within a daemon, if it is going to process more than just a limited amount of email.
 
 == Configuration