error moving messages to mailbox "". ?

Using my 2009 Mac pro: OSX 10.13.6

In the past few weeks, I have been getting the error shown on the above pic. I get it when I try to copy all the messages at once in my spam or junk folder to move to the trash (delete key). For some reason this message or what is happening, stops mail from adding my selected messages to these the trash folder. Some times this error message doesn't appear right away and I find it on my desktop that evening.

The result is that all the junk and spam come into my iPhone the next morning. When I click OK (on my mac) and get rid of the error message that evening, everything goes back to normal again.

I am using dreamhost and IMAP. I am not sure if it is an error on their server, but I am going to reach out to customer support to try and track it down. I also have a pic of my "apple mail file tree". I think some folders are dreamhost and some are Apple on this mac. I create a lot of rules on this mac to catch and move spam. Don't know if this could be causing it.

Cheers! and Thanks.