How can I trace the history of an email?

Question

System administration

theoretical situation. Organization No. 1, Aunt Katya writes to Aunt Ira a report on the work done, attaching a PDF file. Aunt Ira forwards the received letter to Aunt Masha in organization No. 2, but edits the source file and the text of the letter, substituting numbers convenient for her and attaching her file. Say, look what such and such Aunt Katya writes to me. Is it possible to know if attachments were replaced or not in an email message while forwarding? Has the text of the original sender changed? It is clear that you can pull the .msg file from the server of organization No. 1 and compare, but maybe there is some other mechanism for this?

Answer 1

sign pgp emails with a signature. It was specifically designed for this.
Aunt Katya writes a letter, attaches a file, signs it. Aunt Ira can send the letter only in its entirety, without changing it - with any change, the signature is not verified and, accordingly, there is no longer any trust in such a letter.

Answer 2

Alternatively, you can remove the hash of the file and store it with you. If necessary, simply compare with the standard.

Answer 3

In PDF, you can disable changes.