icloud filters my dad emails

Also found this Apple article - iCloud: Make a sender a VIP

And from what I see on my iPhone when I go to the Mail app > Mailboxes i have the starred VIP mail folder, and if I tap the blue i in a circle i get my VIP list and I also have the option to add more VIP's from my Contacts list.

Not sure if it would work or not but you could try adding your Dads email address to your VIP list.

Open the Mail app then open an email from your Dad and tap the From name at the top ( Your Dads ) in blue, in the new window tap Add to VIP if you already have him as a contact or create a contact and Add to VIP then tap Done.

Then test an email to see if adding your Dad as a VIP fixes the issue you have.

So you are somehow forwarding your dad's emails to your iCloud account?

To my knowledge, Apple's spam filtering is based on the sender of the messages, not the receiver. They have several back end silent processes that look for various behaviours for SPAM senders.

It could be that the path your dad's messages follow somehow trigger this. Can your dad send you a message without forwarding that arrives in your in box?

And while I can empathize with the grammar thing, this is typically a pretty tolerant community and we all parse ESL posts without judgement. Your grammar is just fine but you don't need to be so proactive here. Your outburst was really uncalled for.