'POP email clients search functionality failing

I am using mail on my iPhone. I have configured it to use the POP protocol so I can look at old emails without worrying about connections to a server etc.. Recently searching my email has been erratic and it has now stopped. I have very large numbers of emails. I raised the issue with Apple and they are saying talk to my email service provider. I am at a loss as to why that should be relevant.

Any insights into email clients using POP search their already downloaded emails? Why would Apples mail client, or any other mail client, need to talk to the email service provider?



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source