Hi Shellock,
Its not straight forward by any means.
One laptop and Apple iphone are configured to the email address affected.
My husband had gone through a check of settings on the laptop with Telstra yesterday and all good.
I checked settings on laptop and iphone tonight as per IMAP settings for Telstra Mail I printed off from the support section of Telstra support. They are all good and ok.
Our virus software is Norton, i'm not an expert with regards to the set up of it, but ive had a quick laymans look and it looks ok to me. Ive done a system check and that all went ok.
I may have to contact Norton?
When my husband sends emails he doesnt get any error messages or bounce back responses.
His clients have not received any bounce back or error messages when they send emails to him.
Once we establish that an email hasnt arrived to either us or the client, the relative email is sent again and it comes through immediately.