Thriller, mailman and lost packages, Adults book

This book is about a man that works at the post office.
Everytime he sees a package that never been picked, he tries to look after where it came from or to whom it was sent.

I read the synopsis on the back of the book and I want to read it but I forgot the name :(

Thank you and sorry for my bad english :/

Possibly Going Postal?

The Lost Letters of William Woolf by Helen Cullen?