hard match domains for automatic group membership

app/jobs/regular/automatic_group_membership.rb

@@ -13,7 +13,7 @@ module Jobs
 
       domains = group.automatic_membership_email_domains.gsub('.', '\.')
 
-      User.where("email ~* '@(#{domains})'").find_each do |user|
+      User.where("email ~* '@(#{domains})$'").find_each do |user|
         group.add(user) rescue ActiveRecord::RecordNotUnique
       end
     end

app/models/user.rb

@@ -721,7 +721,7 @@ class User < ActiveRecord::Base
          .where("LENGTH(COALESCE(automatic_membership_email_domains, '')) > 0")
          .each do |group|
       domains = group.automatic_membership_email_domains.gsub('.', '\.')
-      if self.email =~ Regexp.new("@(#{domains})", true)
+      if self.email =~ Regexp.new("@(#{domains})$", true)
         group.add(self) rescue ActiveRecord::RecordNotUnique
       end
     end