This is a recent problem. When using SpamSieve with Apple Mail on my Mac Pro I usually select all the damn spam messages and then delete them. Lately I am unable to delete more than one message at a time from this mailbox. The highlighed messages sort of become faded when I hit the delete button but they don’t go away. So what should I do??
The storage and deletion of messages is entirely handled by Mail; it is not affected by SpamSieve. Is the mailbox stored locally or on a server? It sounds like maybe you need to choose View > Hide Deleted Messages so that Mail doesn’t show the deleted messages in gray.