"Thanks for being so understanding about the issues at the post office! Sometimes things just get l ... " (more)ost. Sorry if this issue inconvenienced you in any way. I hope you have a wonderful day and a Merry Christmas!"
"I'm so sorry your shirt didn't get to you. I promised I shipped it, I don't know where ... " (more)it could be. I'd be happy to send you the other shirt if you want it."