Does putting email into folder upload it to IMAP server?

After I set up an email account using the E-Mail preference, all mail on the server was downloaded to folders in my home directory. But, it doesn’t look like it goes the other way. Sent mail doesn’t get uploaded to Sent on the IMAP server. Dragging and dropping messages from the inbox to folders doesn’t upload them to their respective folder on the IMAP server. Is this how it is or do I need to configure something to enable this expected behavior. Thanks.