Thank you for your quick response. I've gone into Settings- Mail, Contacts,Calendars- Accounts. I have an iCloud account and two other accounts already on IMAP. Not sure if I should be looking elsewhere. Do I need to look at my PC settings?

When I go into Windows Mail on my PC, all of my emails on my iPhone disappear with no trace, apart from the deleted ones in the Trash folder. I've also noticed that some emails which I've read on my iPhone do not appear on my PC. I have two email accounts and it happens with both of them. My...