Folders missing

I have noticed that I’m missing some olders and the emails they contained. Can anyone help?

A little more detail would be helpful–

1.  What type of account (gmail, etc.)
2.  Can you log into a web client and see them?
3.  Any error messages?

It’s a cox.net email account (imap). I move the emails into local folders in eM Client so they’ve been deleted from the web client. No error messages. I just happened to notice that some (not all) of the local folders are missing.

That is very strange.  I am a Gmail user, but when I do what you describe it works perfectly for me.