Background:

An anonymous email was received at a business in the US around Aug 2020. The email contains the sender's Internet address which can be potentially used to trace and de-anonymize the sender from a group of suspects. The challenge is to narrow down who the sender could be amongst 5 suspected people. Based on the computations, a court order will be petitioned to track down the email sender.

Suspects

One of the vendor has an axe to grind against one of the employees so there is a very high degree or probability that it is Vendor called Bay who is the sender of the email. The vendor is in cahoots with an internal employee who places purchase orders with the vendor. Vendor 1(Bay) is in cahoots with Person 2(Boss). Of the 5 parties, 3 are vendors - vendor 1(Bay), vendor 2(Solar), vendor 3(Rapid). The other two people, person 1(peer) and person 2(boss) are believed to be inside employees who sent the anonymous email from their home to create the email nuisance. Vendors [v1,v2,v3] Persons [p1,p2] ( use your own notations but please describe and represent the problem mathematically) The employer's email server contains the sender's IP but the employer will not simply give the IP address to the requester. If we get the sender's IP, then we can use the help of the court to de-anonymize the sender. Who can be the sender ? What is the probability and how to narrow down to the email sender. Use math, common sense, intuition to describe your answer. Comparing the vendors to the insider persons, the chances are much higher that it is one of the three vendors. If we compare the three vendors with each other, the disgruntled vendor, Vendor Bay ranks on top of the list. If we compare the inside persons with each other, then the chances of the anonymous email being sent by one of the inside person is 50-50 but we need to keep in mind that person 2 (boss) is in nexus with Vendor 1(bay) and there is more suspicion that it is person 2 but this is a speculation.

Goal is to mathematically describe the problem and calculate probability.

1. Who is the most probable suspect - who could have sent the anonymous email ?

2. What is the rest of the probability of the vendors ?

3. What is the probability that it is an insider job ?

4. Describe what kind of a problem this is ?

5. What will increase the chances of finding the sender of the email ? To get hold of the email or information from the employer would be best using a court order. Email service is operated by Microsoft, so a legal notice can be given to Microsoft as well.