Somthing is deleting my emails

I am using Windows 10, and I don,t like it. My emails started to disappear maybe a month ago or so. I also have an old PC with Windows XP. My son installed the dropbox some 8 to 10 months ago, which is supposed to transfer files between my laptop and pc. I have not deleted emails from the xp, as I know this could happen, but if I delete emails from my laptop I don't think anything is deleted from the xp. O man, I hop there would be a browser with just the most basic stuff in it, and easy to use. I can see some emails in the All Mail. Thank you. Aarno