apple mail app doesn't download some messages via IMAP

apple mail app doesn't download some messages via IMAP

Hi,
I've recently set up our company's emails via IMAP instead of POP (as I'm not able to login via pop anymore for some reason...) and it seems that not all of new incoming emails are downloaded via Mail app on osx. I can see those mails within zoho web client however... IMAP settings done accordingly to zoho instructions. There are no tags presetted, there is no additional spam filter...
Any hints?