= Distributed James Server &mdash; Custom Mailbox Listeners
:navtitle: Custom Mailbox Listeners

== Writing additional listener

An extension writer can write new additional mailbox listeners.

To do so, extend the *GroupMailboxListener* defined in the *mailbox-api*.

Here is the dependency:

....
<dependency>
    <groupId>org.apache.james</groupId>
    <artifactId>apache-james-mailbox-api</artifactId>
</dependency>
....

Here are the methods you can implement:

....
    void event(Event event) throws Exception;
....

allows you to specify the business logic you want to execute upon new events generation.

....
    boolean isHandling(Event event);
....

Allows to know if this event is worth execution, and should be sent on the EventBus. This avoids execution of non
handled events and can save some IOs.

== Registration of custom additional listeners

Your custom additional listener needs to be in the *extensions-jars* folder.

You need to register its fully qualified class name in xref:configure/listeners.adoc[listeners.xml]

== Events

Your listener will be called for the following events:

 - *MailboxAdded*: A new mailbox had been created
 - *MailboxDeletion*: A new mailbox had been deleted
 - *MailboxRenamed*: A mailbox was renamed
 - *MailboxACLUpdated*: The rights of a mailbox had been changed
 - *Expunged*: Some messages had been deleted
 - *FlagsUpdated*: Some message flags had been updated
 - *Added*: New messages had been added to a mailbox
 - *QuotaUsageUpdatedEvent*: The quota of a given account had changed
 - *MessageMoveEvent*: A message was moved between mailboxes. This carries an account wide information. Spoecific
mailboxes event (Added & Expunged) will be emitted as well.

== Example

http://james.apache.org/howTo/custom-listeners.html[This page] provides a working example for writing additional custom mailbox listeners.