Deleted emails still found by spotlight

If I search with Spotlight on my Iphone using an (partial) email address or keyword, my entire mail history with such an address turns up on my Iphone including emails i have deleted. I even removed the mail account in whole, but the data still turns up. The emails (including entire back and forth conversations) don't even exist anymore on any mail server. Is there a way to delete this information permanently from my Iphone?