When and how do I get a reply

Lets look at this.

I have no idea what " At present I cannot receive emails as previously" means to you. I am not aware of what was your defaults previously or what they are now! Are you asking for guesses? My guess is you don't like threading and want to turn it off. https://support.mozilla.org/en-US/kb/message-threading-thunderbird#w_disable-threading-on-a-folder

As for your mobile device, ask Telstra perhaps as I would guess they supply it. There is no Thunderbird app for Mobiles so it is outside the purview of this website.

May I ask whether Thunderbird has recently been upgraded " I now cannot send or receive emails and am wondering whether it is Thunderbird or Telstra at fault

May I ask whether Thunderbird has recently been upgraded " I now cannot send or receive emails and am wondering whether it is Thunderbird or Telstra at fault

Thunderbird gets an update about every four weeks. To check exact release dates check here https://www.thunderbird.net/en-US/thunderbird/releases/

My guess is it will be neither Telstra or Thunderbird but your antivirus product. Norton are the flavour of the week blocking folk at the moment, but it changes frequently as to which product are topping the charts here. Norton is mentioned in dispatches very frequently however.

But you might want to actually post your error message so I can do more than guess.

Thanks for your efforts Matt.

Eventually I was able to re-establish my email service to a certain extent.  I can now send/receive emails. And for a short time the previous status was returned.  But in the slow laborious chats with Telstra , instead of removing the additional email accounts which I do not need they have somehow guided me into losing the whole business and private history (ie all my folders) of the original account for the past twenty or more years. My original account is active but it contains only INBOX SEND and TRASH. The original folders have disappeared. I now have two additional email accounts which just hold recent emails ( since their recent creation) and are obviously superfluent to my needs.

Are you aware of any method to retrieve those emails from a server perhaps ? Are they lurking somewhere or have they gone for good.

Telstra keep appologising for the stuff up and I don't believe they have the skills to deliver. I'm hopeful you can suggest a solution. I'm happy to engage a technician to try if you think they may be able to recover all the folders off the server