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The Empty Email with No Subject or Body (illustration)
FILE No.30Unsolved

The Empty Email with No Subject or Body

Difficulty ★★☆about 5 minEveryday MysteryHow email worksAddress fields
The victim’s empty email reached three people. Use what the To, Cc and Bcc fields show to find the person who lies.

Case Record

Takanashi, who worked in accounting, was found dead in the company warehouse. Just before dying, Takanashi had sent an empty email with no subject or body.

The recipients: To was Arakawa, Cc was Imai and Bcc was Toyama. The names of Bcc recipients are not shown to the other recipients.

The three said the following.

  • Arakawa: "An empty email came, so I thought it was sent only to me and Imai."
  • Imai: "I know it arrived, but I don’t know who else got it."
  • Toyama: "I never received such an email."

The mail server records show that all three received it.

Your question

Who is certainly lying?

Case Files

Evidence

Diagram

Who the mail was sent toFieldRecipientVisible to others?ToArakawaYesCcImaiYesBccToyamaNoServer record: all three received it.
Diagram

Timeline

  1. Takanashi sends an empty email.
  2. It lands in all three mailboxes.
  3. Takanashi’s body is found in the warehouse.

Hints

If you get stuck, open the hints one at a time, in order.

Open hint 1

Recall the differences between To, Cc and Bcc.

Open hint 2

How do the address fields look from each person’s side?

Open hint 3

Whose statement conflicts with the server record?

Solve It

Your question

Who is certainly lying?

Choose the answer closest to the truth.

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The Truth

Toyama

The answer is Toyama.

Arakawa can see only himself in To and Imai in Cc, so it is natural to think "only me and Imai." Imai’s "I don’t know who else got it" is also correct, since Bcc cannot be seen.

Toyama, however, says "I did not receive it," although the server record confirms receipt. A Bcc recipient’s name is hidden from the others, so such a person may assume "no one knows," which makes lying tempting. The one who is certainly lying is Toyama.

Does it match the record?PersonStatementMatches the record?ArakawaOnly me and ImaiFits what he seesImaiOthers unknownFits what he seesToyamaDid not receive itContradicts the record
Diagram of the solution

Key Points

  • The address fields look different to different people
  • Only a statement that conflicts with the record (log) is a certain lie
  • Think about what each person can and cannot see

Why people get fooled

You are drawn by the oddness of an empty email and never check each statement against the address fields.

Similar tricks

  • The type that checks testimony against system records
  • The type that notices differences in what each person sees

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