G'day .
Had a phone call from a business I use.
Office lady informs me I have not paid an account - which had been emailed to me she said.  I claimed no knowledge, so she said she'd send it again - like right now.
Gave it five minutes, and rang her , as I had nothing from their business.
Unusual thing is that an email from another organisation, sent the same time, popped up quite OK.
How can that happen?
I sent myself a test mail from my Gmail account to the Bigpond account that is mucking up, and it did not turn up either.
Any suggestions as to 1. Reason,  & 2. What to do about it!

TIA    Aussy Harold