Help needed on a Salesforce Trigger manipulating Contact Object

Whenever you send an email, you need to create an activity under that record. This helps you in tracking the last email sent for that record.

Trigger should be developed on Task.

trigger TaskTrg on Task (after insert) {

List<Contact> lstCons = new List<Contact>();
for(Task tObj : trigger.new){
if(tobj.whatId != null && string.valueof(tobj.whatId).startswith('003')){
Contact con = new Contact(Id=tObj.whatId);
if(tObj.subject.contains('Email')){
con.LastEmailSentTime__c = System.now();
}

con.LastTaskCreatedTime__c = System.now();
lstCons.add(con);
}
}

if(!lstCons.isEmpty())
update lstCons;

}