Long time eMclient paying customer, recently updated to version 9. Its super super buggy.
Don’t know how to report the issues exactly but I recommend to stay away from version 9 for the moment.
I had to do some massive email movements between accounts, Gmail / Google Workspace and in the end I had a ton of duplicated labels, labels not nested properly and a whole bunch of connectivity and random server errors and infinite loops.
I will probably revert back to version 8 for now, I already worked through the issues myself but something is wrong with version 9.