Junk Mail on I Pad not filtered

Try these steps, it may learn from your actions:

Report junk mail

Filtering junk mail at the server level is only part of the solution. You can report messages as junk in the Mail app and help filter junk mail in iCloud. Then future messages from the same sender are marked as junk.

To mark a message as junk:

• On your iPhone, iPad, or iPod touch with iOS 7 or later, open the message, tap the Flag at the bottom, then tap Move to Junk.
• On your Mac, select the message and click the Junk button in the Mail toolbar. Or you can drag the message to the Junk folder in the sidebar.
• At iCloud.com, select the message, then click the Flag button and choose Move to Junk. Or you can drag the message to the Junk folder in the sidebar.

From this article:

Identify and filter junk mail in iCloud - Apple Support