Police would like to speak to him following the theft of a parcel around 12.15pm on Thursday (23 December) from the Post Office in North Street, Chichester.
The contents of the parcel are thought to be worth around £1,500.
Investigating officers are keen to identify the man pictured as they believe he can assist with their enquiries.
The man entered the Post Office just after 12.10pm and attended the currency exchange desk. He is thought to be in his 40s, wearing a grey woolly hat, green long-sleeved top, black body warmer, blue jeans and carrying a number of shopping bags.
Anyone who recognises him or who has any other information which could help officers with their investigation is asked to report it online or call 101 quoting serial number 609 of 23/12.