This is indeed a serious problem if read-only shares aren't really read-only :( I have to test this on our system because this is really disturbing.

I have tried it several times and have always had the same problem.
Among other things, they told me that they replicated the problem some time ago.

Please give it a try and let me know if it gives you the same problem

Hello all, 

I want to let you know that the issue with IMAP read-only permissions has been resolved in Build 7852 which is available for download here: https://www.smartertools.com/smartermail/downloads

I also see the a read-only folder can be marked as read/unread via the right-click context menu. I will get this reported to the development team for their review. 

Build 7852

I tried, and now even from an imap client it does not allow deletion.
It gives no error, the client says I deleted but then actually doesn't. I don't know if an error can be returned to imap ..

But the system still has problems.

If a share is read only it should be allowed to read only.
Instead via webmail it is possible to change the status of a message contained in a shared folder from read only to read / unread

Via client imap the behavior is even stranger.

read / unread are only applied locally without any sync with the server

Hello all,

We've had many conversations about the read-only capabilities in regards to IMAP folders and we're not seeing a good solution with our current implementation.

The way we're allowing users to subscribe to shared folders is not the normal way to connect to a share via IMAP.  Normally you would have to connect to the other person's mailbox to view those folders and wouldn't have the option to directly subscribe from your own mailbox.  This is why you see undesired results when trying to delete, flag/unflag, and mark as read/unread against shared folders.  We properly return error codes but unfortunately each client seems to react to these errors differently.

Because of these inconsistencies from each client, we've decided to not allow users to connect to read-only shares via IMAP.  It doesn't bring the correct user experience in its current implementation.  However, we will allow users to subscribe to full control folders.  We'll be generating a KB article to explain our reasoning around this change for future reference.

We apologize for these sudden changes but having the correct user experience made this the right call.

Thanks Larry
Let's see if I understand correctly.

In future versions, smarteremail will no longer be able to subscribe to shared folders as read only.

However, the read-only shares will be visible in the webmail. Quite right?

You are correct.  Webmail will have read-only shares visible to users but IMAP clients will not.

In addition to Larry's comments above, in the webmail interface, we do allow the read/unread status of read-only folders to be modified. Please note that this behavior is not new; the interface has been behaving as such for some time. However, after further discussion, we decided to keep this behavior for the user experience and because a user with read-only permissions is allowed to read the messages, including marking them as read. Any other actions that would sync back to the owner are not permitted.