30-year-old Pratap Behera, a resident of Astarang area in Puri district, had sent the mail from a cyber cafe, Commissioner of Police B K Sharma said.
Sharma, however, ruled out the involvement of Maoists in the incident and said that Pratap had sent the letter in the name of his cousin Prakash to settle a personal score.
"Pratap opened an e-mail account in the name of Prakash and sent it to the CMO," the officer said, adding that it took about eight days to locate him.
The accused was produced before the sub-divisional judicial magistrate's court here.
"If you deliver speech at Cuttack, this will be the last public address in your life," the mail had threatened the chief minister.
It had also demanded release of Subhashree Dash, wife of Maoist leader Sabyasachi Panda, which had led to suspicion of the banned group's involvement.