Hi.
Here corporate email is company's (depends on country) and of course I don't have enough technical knowledge so I told what I want to do (user's specific spam treatment).
So why is it on you to take care for a technical problem like spam handling? Talk to the administrators of the mailserver(s) to find a solution for the spam problem on server side. And some people will have access to these mailboxes, why do they not mark spam by themselves? If this is not sufficient a spam/ham learning system on users side could be established, so authorized users could mark spam for themselves. But all these topics are nothing that is related to roundcube, which is (as already stated many times before) just an IMAP client on the web.
Accounts=are like "sells, customerservice, technicalsupport", no one is liked to particular people.
Does not matter. If you were authorized to open these mailboxes you would have gotten or easily get the credentials from the appropriate authorities. If I want someone else to handle spam in one of my mailboxes (which I do not!) I would grant him the access, so easy.
Bye, Daniel