Zoho mail on Mac and iPhone won't sync

Zoho mail on Mac and iPhone won't sync

Hello, need some help please. My inbox sync on Mac and iPhone so if I get an email it arrives on both, if I delete it deletes on both. My issue is SENT items. If I send on iPhone it does not appear in sent items on Mac, and if I send on Mac it does not appear in sent on iPhone. Also it seems I have 50 or so deleted items in the bin on Mac, but only two in the bin on iPhone. 

I would just love for whatever happens on one, happens on the other. Thanks for any help.