May be but not confirm,Courier services by-self tell the person that we dont have authority ,i remembered when i first time went to TCS they told me its post offices matter not us,we cant do this only pakistan post send this application in the box.you should better to go post office....."tum ja k express courier walo ko pakro jinhon nay farud kya hye".but you should wait for few days as i also not recevied mine letter for the post of SI,but received two other letters from the same department.