The most recent theft happened Sunday on Joshua Tree Circle.
Surveillance video from early Sunday shows two suspects drive up to the mailbox that's shared by multiple homes. One pries open the mailbox and the other cleans it out.
The Stockton Police Department said it's not the first time thieves have hit this neighborhood.
"They'll [officers] go out and patrol those areas where the mailboxes are just to try to have a visible presence so that they can deter that kind of activity," said Officer Joe Silva.
The police department works with US Postal inspectors to find out who's behind these break ins. Stealing mail is a federal crime punishable by up to five years in prison according to the USPS.
"They'll go through the federal court system instead of the state court system and usually that comes with more severe penalties," said Silva.
With the holidays quickly approaching the department says thieves target homes more. Officers want residents to be vigilant with their mail and deliveries. The USPS suggests not leaving mail in mailboxes overnight.
For Brandi Cross, whose mailbox was broken into Sunday, she worries about her letters being stolen. She said that's her only form of communication with her fiancé who is at Army basic training in Georgia.
"Why do you have to steal other people's stuff? Obviously they don't care about the importance that any of this mail means to us," said Cross.
Anyone with information on this break in or other break-ins are urged to contact the Stockton Police Department or US Postal Service.