Police said Ritu Sharma had an affair with Amit Jain, who was married to some other girl some time back.
Annoyed over the issue, Ritu sent the e-mail from a fake id to Chief Minister's Office, DGP, Jaipur Police commissioner and other police officers yesterday.
"The sender unspecifically mentioned the name and postal address of Amit, resident of Pratap Nagar, in the e-mail and said that a letter having information about the plan of bomb blast in Jaipur on June 13 was about to be delivered to him," Additional Police Commissioner Girraj Meena said.
"It was also mentioned in the e-mail that there were information related to Army cantonment in the letter following which the Army as well as Central Intelligence authorities were informed and investigation started by police," he said.
A police team rushed to the postal address mentioned in the email and held Amit.
He expressed ignorance about such e-mail and letter and suspected that her former girlfriend Ritu may be behind this, police said.
Meanwhile, the IP addressed of the computer which was used to create and send the e-mail was traced to a cyber cafe in Vaishali Nagar.
The cyber cafe owner verified that a woman named Ritu had visited the cafe yesterday.
Thereafter, the woman was today picked up for questioning and later placed under arrest under IT Act for her involvement in the matter, police said.
Ritu is an MBA degree holder and presently unemployed, DCP (West) Dr Ravi said.