Daniel Lynch, 33, of the 900 block of Pheasant Run in Newark, was arrested on Friday.
Police say they were contacted by Lynch's ex girlfriend on Thursday, who said Lynch had repeatedly called her and sent her emails and text messages, even after being told she didn't want any contact with him.
She had been receiving those unwanted messages over the course of a year, she told police.
Investigators say some of the emails were sexual in nature.
Officers found Lynch at his workplace on Friday where he was arrested.
Lynch was charged with stalking and was released on $2,000 unsecured bail. He was also ordered to have no contact with the victim.
Police say there may be other victims and ask anyone with information to contact the New Castle County Police Department at 395-8172/573-2800 (Attn: Officer A. Knorr).