The email address where to send extension of IED is skilled.support@homeaffairs.gov.au.
First entry to Australia
If you are unable to make your first entry to Australia as the holder of one of the following visas due to travel restrictions related to COVID-19, please refer to the attached Information for First Entry to Australia:
§ Skilled Independent (subclass 189)
§ Skilled Nominated (subclass 190)
§ Skilled Regional (subclass 489)
§ Skilled Work Regional (subclass 491)
Individual emails will not receive a response.
Here's the attachment.