You can report your absence to the IND via the Secure email starter on the page Submitting your documents. Always state if someone will be handling your cases in your absence. The notification will be linked to you as the authorised representative in the INDIGO system by the IND.
You can send a message to the IND in individual cases, for example, if you want to request an extension due to your absence. Refer to your earlier absence notification in that message.