Instant Email Notifications with IMAP Transporter

Modern users expect email notifications appear instantly when a new email arrives. 4D 21 R3 introduces support for IMAP IDLE notifications, bringing real-time email awareness directly into your applications. Instead of relying solely on periodic synchronization, you can now react instantly when a mailbox changes.

HDI IMAP Events

With IMAP IDLE support in IMAPTransporter, your 4D application can subscribe to mailbox notifications. Instead of asking: “Did something change?”, the server tells you: “Something just changed.” And not just new messages. You can react to:

• A new email being created
• A message being deleted
• A flag being modified
• A change in mailbox state

To support mail notifications, we extend the IMAP capabilities of 4D by enhancing the IMAP New transporter command with a new listener parameter. This new listener object allows developers to register callback functions.

Supported Notification Events

The parameter.listener object supports the following callbacks:

• listener.onMailCreated(): Triggered when a new message is detected in the current mailbox.
• listener.onMailDeleted(): Triggered when a message is permanently deleted.
• listener.onFlagsModified(): Triggered when message flags change, for example, when a message is marked as seen.

Start / End Notifications

The 4D.IMAPTransporter object exposes a notifier property with lifecycle control methods:

• notifier.start(): Subscribes to server notifications and activates your IMAP notifier.
• notifier.stop(): Stops the subscription to the server and your IMAP notifier.

For example, you can implement a class that is responsible for managing your email listeners centrally:

// Class IMAPListener

// Triggered when a new email is created on the server
Function onMailCreated($transporter : 4D.IMAPTransporter; $event : Object)

	ALERT("You have a new mail!")
	
// Triggered when an email is deleted
Function onMailDeleted($transporter : 4D.IMAPTransporter; $event : Object)
	
	ALERT("Message deleted")

// Triggered when message flags change (e.g., read/unread)
Function onFlagsModified($transporter : 4D.IMAPTransporter; $event : Object)
	
	ALERT("Flag modified")

And you can start the notifier when it’s needed in your code:

var $parameter:={}
$parameter.authenticationMode:=IMAP authentication OAUTH2 // Using OAuth2 for authentication
$parameter.host:="Outlook.office365.com" // IMAP server host
$parameter.port:=993 // IMAP SSL port
$parameter.accessTokenOAuth2 := $myToken // Token received from the OAuth server
$parameter.user:="myadress@email.com" // User email address
// Listener Intialization 
$parameter.listener :=cs.IMAPListener.new()

var $myTransporter:=IMAP New transporter($parameter)
// Start the notifier
$myTransporter.notifier.start()

Conclusion

With IMAP IDLE notifications integrated into IMAP New transporter, 4D applications can adopt a real-time, event-driven approach to email synchronization. Users already expect instant updates from their messaging tools, and this enhancement enables your 4D solutions to deliver the same seamless experience.