You can block spam, phishing attempts and other malicious emails by setting up spam blocking/filtering on your iPhone.

Individual email blocking/filtering settings can be easily set at once.

Using the "Simple Settings" is recommended because it automatically turns on the "Reject Spoofing Mail" function.

My SoftBank login > Mail Settings (MMS) > "Spam Blocking Settings" > "Simple Settings"

Individual spam filtering settings can be set as needed.
It is recommended to turn on the "Reject Spoofing Mail" function.