On my iMac I use wanadoo.fr (Orange) as my email provider, with Eudora as a front end. I can set filters to block undesirable email in either wanadoo or Eudora. How do I set filters in iPad mail? I have accounts both
for wanadoo.fr and also for me.com

You can't set filters (rules) on the iPad itself.

If you visit the icloud.com site you can set up some rules there. These rules take affect on the server, before the email is sent to the iPad. If you are talking about Junk mail, then just routinely move what you consider junk mail to that folder. The server will catch on after a while. To keep stuff out of Junk mail, create a contact with that email address. I keep a category in my contacts just for un-junking certain sites.

Your other account may have the same ability. I don't know.