Bonjour, Sans réponse, après avoir relu des posts approchants, je ma suis autorisé à mettre à jour mon TDB ( je n'avais rien à perdre...) Et ça marche ! Tdb a reconnu mon profil, et chargé en POP les mails reçus de ma boite Orange ( préservés de l'effacement par un délai suffisant ) Merci à Mozilla Thubderbird

I am pleased that all is ok. I was just about to respond, as I first had to translate it. I encourage doing a backup of profile to protect against future outages. Here are the steps I always recommend:

here is the info in brief steps:

BACKUP

1. ensure thunderbird is not running
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media

RESTORE

1. ensure thunderbird is installed and NOT running
2. enter %appdata% in search window on task bar and press Enter key
3. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
4. start thunderbird and all should be there

Thanks David,

Bad luck : the next day my first message was refused.
After some research, I ended up reconfiguring the IMAP server and everything runs  fine.
I did two tests including one after restarting the PC.
I just hope that tomorrow my messages will continue to go through,

Thanks again.

You are very welcome. I was glad to assist.