I pad2

Do you use a PC too Lucky? Log on to your email provider's website on that and delete all the necessary emails from inbox, junk and trash. The the deletions should sync through to your iPad too. Hope that works.

Are you using Outlook ? And are the email addresses strange a bit like hello @fred.sim.ik

There has been a spate of these emails , all with odd addresses and you cannot block them because Outlook says its not a proper email address.

They often appear with a flag.

As far as I can see there is no real work around if this is the problem. You can seriously cut them down by setting your privacy setting to Exclusive but then a lot of the stuff you want will go into junk along with the unwanted stuff.

Hope this isn't your issue and its something solvable.

I guess you are using the iPad's email client and not Outlook? Alima's suggestion should work. You may even be able to access your email provider's website via your iPad to delete the mails but you may find that you don't have access to all the tools/functions available on the website.
The other possibility is that you are using the iPad's email client and have switched on the backup to iCloud. If you open iPad's settings, open the iCloud settings as well and check whether you have toggled the Mail button to 'On'. If you have, turn it off. It may take several goes to delete them all but they shouldn't keep coming back.
There are a couple of other things you could try but you would need to provide a bit more information. Let GN know via this forum how you get on.