Another email, the fourth since the Delhi High Court bombing, on Friday claimed that the deadly blast that killed 13 people was the handiwork of the homegrown terror group Indian Mujahideen.
An officer of the NIA stands with the evidence collected from the site of a blast at Delhi high court in New Delhi.
The latest email was sent from firstname.lastname@example.org, the same address from which the second message was received on Thursday.
It sought to confirm the third communication, received earlier Friday, attributing the attack to the Indian Mujahideen.
The email was sent to some media houses in Delhi.
It says: "Namaste media bhayyon. Third mail apko mila wo hamari taraf se hi bheji gayi thi (The third mail was sent by us)". Flurry of email foxing security agencies
The India Mujahideen had planted the attack "after a lot of thoughts", the email reads.
It also warns that the next attack would be at a crowded place in Gujarat's Ahmedabad. The third email, traced to a server in Moscow, had warned of a "cruel" attack in Ahmedabad.