Backend Mailbox API Feature Requirements

• This list of features we need to support, or want to support by the backend API.
• POP3 needs

  • 'username+password' -> 'inbox' mapping,

  • listing of the content of inbox, with subject only (?)
  • getting the content of an email by it's id
  • deleting messages from the inbox
• SMTP needs

  • 'email address' -> 'mailbox' mapping

  • putting an email into the mailbox
  • SMTP compliance we should make sure that a message is not normalized or "fixed" before it is relayed
• NNTP needs

  • ???? I don't know

• Internal James API needs (spooling, fetchmail, etc):
  • handling various 'spool' 'mailbox'es, adding and removing items to them.
• IMAP needs:
  • handle mail specific flags (Answered, Deleted, Draft, Flagged, Recent, Seen...)
  • ability to search by various header parameters (From, Subject...), flags
  • handle mailbox hierarchy per user (this would be nice for JSieve also, as I know)
  • shared/readonly mailboxes (this is optional)
  • custom properties for mail, the MIME structure is important, but some useful imap extensions needs others, for example CONDSTORE/QRESYNC as I remember needs a 'transaction number'.
• Other features, which we want to consider comes from the deployment scenarios :
  • db only backend
  • db for the metadata, file system for the data, in maildir/mbox/custom format
  • db less backend, pure file system
  • mixed backend (for example, the user mailbox are in a db, the shared, read only mailboxes are on the disk.
  • jcr backend
  • james servers in front of the same backend (probably db-only, or jcr)

Current API

Here's a class diagram for the current interfaces:

Seems excessively complex

MIME Structure Strawman

Here's a strawman for MIME Structure:

Probably something simple should be enough - some recursion, a couple of interfaces plus access to mail headers, MIME meta-data and Content should be enough.

Factories, Factories and more Factories

Here's a class diagram for the current factory interfaces which create managers and mailboxes:

Again, seems excessively complex. IMHO it would be better to have a canonical mechanism for each function. Concise APIs are easier to learn and easier to implement.