and why should his email gethacked when he keep him safe and probably equipped with the newest antivurus
The e-mail system is painfully insecure due to its age. TLS is a bolt on.
When you write an e-mail and send it - first it goes from your client (web or real) to an SMTP server. That connection probably uses TLS but it might not, you should verify. It is difficult to verify with webmail.
When it gets to the incoming SMTP server, it is no longer encrypted. It is in their server as plain text.
That server then does a DNS lookup for the MX records associated with the receiving domain. Unless the receiving domain uses DNSSEC *and* your sending server enforces DNSSEC, it could be lied to about the answers.
That server then attempts to make a connection to the receiving server specified in the MX record.
That connection may or may not be encrypted and you really have no control over it. The RFC says that the a non-encrypted server MUST be acceptable. Encryption only happens when both support encryption *and* both support a common cipher suite. That may be a weak one like RC4.
When an encrypted connection is used, the certificate is rarely signed by a certificate authority because they never check anyway. They never check anyway because there is no agreed upon list of certificate authorities.
Once the message gets to the specified MX server, if it even was sent encrypted it is decrypted again. And then it is sent to the server where the IMAP/POP3 takes place, and that may or may not be encrypted and you have no way to know.
This btw is why what Hilary did was so dangerous. Within the .gov system, they have control over the servers but as soon as an e-mail is outside their system, they have no control.
Anyway, how fundamentally insecure the e-mail system is is why secret things should not be stored in e-mail.
If you must, encrypt it first using something like GnuPG.
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Using something like hiding your passphrase in a poem - that's called Security by Obscurity and it is a very very VERY bad practice.