Yes. I have a number of tpg email accounts with aliases. I have tested each account and they all work except the account to which one of my aliases is attached (my primary account) strangely this account works WITHOUT the alias (i.e the nnnn@ tpg.com.au address) but gets the error message on the account with the primary alias using my own domain name. the other accounts work using the personal domain name. I have tried shutting down the modem and the NBN box and restarting - nill efffect.   Regards   Fiddler   ... View more

My issue is similar - the "Blessed" NBN has been on & off in my area over the last month I will try a reset. The 550 5.7.1 error has occurred only in the last week.  I too send multiple recipient emails and use an email engine (pdf machine) for large bulk mailouts. ... View more