Does Zoho mail dowload messages even when offline?

Does Zoho mail dowload messages even when offline?

 My question is as above because i have noticed that new messages downloaded via my IMAP client at home appear as READ even if i haven't seen them yet.

The only thing i can think of that is causing this is Zoho downloading them even when i'm logged out of Zoho, thus the message is marked as READ on the server before i have downloaded them at home.

Any thoughts?