Lua Events
Inbucket events can be divided into two major categories, before events and after events.
Before Events
Before events allow extensions to intercept events before Inbucket acts on them. This gives an event handler the chance to alter the processing of, or reject the event entirely.
For example, a before event handler could:
- Immediately reject a
MAIL FROMcommand when the from address matches a particular pattern, returning an error code to the sending SMTP client. - Detect when a message was sent from a staging environment, and ensure it is
delivered to the
stagingmailbox in addition to the recipient's mailbox.
Before events block the active SMTP session while they are running; performing expensive operations in the handlers will reduce the perceived performance of Inbucket; SMTP clients will wait longer to deliver messages, and messages will take longer to appear in their destination mailboxes.
After Events
After events allow extensions to take an action after an event has completed.
For example, an after event handler might:
- Notify an HTTP endpoint that a new message has been received, including the subject line and senders address.
- Write metadata about a received message to disk, and then allow it to be inspected by a waiting continuous integration test by executing a shell command.
These events are processed asynchronously with respect to the rest of Inbucket's services; performing (reasonable) file or network operations within them will not degrade Inbucket's performance.
Event Flow
The order in which events occur is: