Does the e-mail send from an id to the same id requires encryption and other security checks?

Question

I have noticed that Gmail is not encrypting the mails send from an id to the same id (When From address and To/Cc address are same).

Is encryption really required in the above scenario? Necessity of other security protocols check?

Background : I could not find the encryption details in the tag security: Standard encryption (TLS) and below checks are not done while checking the original message.

1. Sender Policy Framework (SPF)
2. DomainKeys Identified Mail (DKIM)
3. Domain-based Message Authentication, Reporting and Conformance (DMARC)

Answer 1

It depends. If you address a snail mail letter to yourself (i.e. same sender and recipient) and put it into a public letterbox than its probably better to close the envelope (i.e. protect the letter). If you instead live alone and leave the letter to you on your own kitchen table, then protection is likely not needed.

If you send a mail to yourself using the GMail web interface then there is likely no "normal" mail transport (i.e. SMTP) involved at all. This means anything like SPF, DKIM, DMARC and SMTP encryption play are irrelevant and you will not find any traces of it. Even if you directly connect with authenticated SMTP to Google's mail server to deliver the mail, SPF, DKIM and DMARC are not relevant. These are only relevant when delivery origins from some external mail infrastructure outside of Google.