The sources said the threat mail claiming to be from terror group Indian Mujahideen has been traced to a cyber cafe Kundu Computers in Behala area of Kolkata.
They said prima-facie the mail looks like a prank but further investigations are on.
They said the cyber cafe does not have close circuit cameras installed or any log register.
The hotel had recently made a complaint to Delhi Police alleging that it had received a mail threatening to carry out 26/11 like attacks. The mail claimed it was from Indian Mujahideen.
The sources, however, said a Bengali surname was linked with the email address which led to suspicion that it could be a prank.
They said further investigations are being carried out to ascertain the sender of the mail.