Hi checker,
Getting spam From: your own email address is a spammer tactic to help get their email past spam filters.
Who is your email service provider?
I don't recommend blocking From: your own email address, though I do agree with you it that it technically should be allowed if you really want to block From: your own email address.
Do you have your own domain name? Can you enable SPF?
If you are getting bounces back to your email address that's called a Joe Job, but in this case it appears to be spam From: you direct to your account, not bounces back at your account due to a spammer having used your email address as the From: on one of their spam blasts.
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