1. Spam protection:

- A spam folder
- Ability to mark mails as spam
- Maybe the ability to add a list with key words and algorithms for automtaic spam detection

2. The ability to subscribe additional folders from a mail service via IMAP

3. An option, that the mail will be downloaded, but removed from the web server.

4. Possibility to embed a visrus scanner for automatic virus scanning, if the mail will be opened/downloaded.