Hi @hdt01969 . Your TPG email address is your username followed by @tpg.com.au
Username is the username associated with your TPG account, not the username you have chosen here in Community, although they could be the same.
Regarding Apple and eBay, it is strange that they would require that.
@hdt01969 . I wouldn't have thought so, but the mail.tpg.com.au domain might point to tpg.com.au.
If you have a TPG email address, you can get someone to send a test email to both format email addresses. Or, create a gmail or hotmail address and send to TPG addresses.