In general, you can delete the messages whenever you want, as long as they are in the correct “folder.” B8 has its own database of tokenized words and their “spamminess” scores, and it doesn’t rely on what’s in the inbound messages.
The reason for recommending deletion only when they are in the right “folder” is that b8 undergoes a learning and unlearning process for spam detection. Moving the email between spam and inbox in Flamingo triggers this process. Deleting it when it’s in the wrong place would cause you to miss the opportunity to build a robust token database.
If you want, leaving about ten spam messages and ten non-spam messages is a good idea (and if they are localized, even better). B8 needs to build a database since it operates on lexical affinity. Ultimately, the Bayesian filter is a statistical tool to calculate the likelihood of something being probable or improbable, so providing it with a solid foundation to build its database is excellent.
