I read the announcement 23 Nov account opening information for Australian addresses.
The Holder ID is required access the sign up. Can't see any mention of a second letter.
Seems disadvantageous to many investors being reliant on a 2nd postal service at Xmas as you mention.
Here's me thinking the Couriered Registry letter ID and your details lodged with automic verified. Ie email and phone number was all that we needed for a seemless transition.
IHL Price at posting:
4.1¢ Sentiment: Hold Disclosure: Held