Schedulable Duplicate contact finder and email notification

// Comment

//Scheduled class for checking duplicate contacts and send an email with the duplicate emails.
//Code can be resued by changing the SOQL and search criteria

global class duplicateContactCheck Implements Schedulable
            {
            //String to store the html email content
            public String htmlOutput{get;set;}
            
                       global void execute(SchedulableContext sc)
                        {
                                    htmlOutput='';
                                    duplicateContactMerger();
                                   
                        }
                        
                        //Method to check for duplicate contacts based on email.
                        //Sending all the duplicate email address to predefined email address
                        public void duplicateContactMerger()
                        {
                                    AggregateResult[] groupedResults = [SELECT Count(Id),Email FROM Contact GROUP BY Email HAVING COUNT(Id)>1];
                                    system.debug('size--'+groupedResults.size());
                                    htmlOutput='
Multiple contacts found for the following email addresses:
';
                                    for(AggregateResult ar:groupedResults)
                                    {
                                    htmlOutput = htmlOutput+ar.get('Email')+'
'; 
                                    } 
                                  htmlOutput=htmlOutput+'';
                                  
                                  //Sending email only when duplicates are found.
                                  if(groupedResults.size()>0)
                                   sendmail();
                        }
                        
                        //Method to send email
                        public void sendmail()
                        {
                                    Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
                                    
                                    //Hard coded email can be replaced with Custom Setting also
                                    string [] toaddress= New string[]{'test@test.com'};
                                    email.setSubject('Duplicate contacts');
                                    email.setHtmlBody(htmlOutput);
                                    email.setToAddresses(toaddress);
                                    Messaging.sendEmail(New Messaging.SingleEmailMessage[]{email});
                        }
                     
            }