What OS?

And can you post a screen shot?

Hi Wayne, Not sure what your question is...a dinosaur I am afraid. 'OS' does not mean anything to me and I don't think I have ever attempted a 'screen shot'!! Many thanks for your response though.

I see that you are on Windows 10.

Please post a screen shot in this topic - instructions at https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

Hi Wayne, Herewith screen shot.

I have tried the message in 'conversation' and do get the entire thread. However as this problem has only just occurred I am finding it a bit of a bind to always go down this route. I am puzzled as to why things appear to have changed......it is very possible that in my ignorance I have pushed a wrong button somewhere!!

Not sure about POP or IMAP!! or how relevant that can be? It has not changed as far as I know. mail provider is BT

Many thanks for your help. I can now confirm that my account is IMAP !

But I still have the problem that there is no indication against my inbox items that a reply has been sent. I have been using Mozilla for about two years and not seen this problem before!! Is a recent upgrade the cause? If so can I get back to the previous version?

Hi Guys I am pleased to be able to confirm that the arrows indicating message replied too or forwarded have magically returned!!

I guess somebody has turned the tap on again!!!

Very many thanks for your support. It is good to know that, for once, it may not be my lack of knowledge with these things that was the root of the problem.

My understanding is that BT have a contact with Yahoo to provide mail services. Simply stated I have lost all confidence in Yahoo to do anything without dropping the ball. So you will probably see random problems as they try and bumble their way to either integrating with AOL and Verizon or into oblivion.