Police in Cornwall are investigating a series of raids on post boxes.
Police believe a sledgehammer was used on the vandalised post boxes
They say 10 boxes have been smashed open and their contents stolen within the last week.
Officers believe Christmas presents and money were the targets for the thieves.
The Royal Mail says any customers concerned their mail has been taken should contact them.
On Sunday night, two post boxes were smashed open in the village of Feock, near Truro, alone.
In each case, a heavy tool, such as a sledgehammer, is believed to have been used to break into the cast-iron boxes.
Sergeant Jim Pearce of Devon and Cornwall Police said: "For this time of year, it's a despicable crime.
"Obviously children are going to be missing out on some of their presents and it is something we would like to solve.
"Hopefully, members of the public can help us to do that."
Feock Parish Councillor John Brock said: "When people are sending Christmas messages to their family and friends, to think that someone can come along and just vandalise post boxes is pretty horrendous."
After one break-in, some of the stolen letters were found scattered in a nearby village.