Contact your email provider. They are on a blacklist.

Thanks for your reply but I don't believe my email provider is on a blacklist -they are orange.fr one of the largest providers in europe and all my other emails arrive safely - any other ideas please

Your faith in Orange is admirable. It is also incorrectly placed. The message is saying the receiving server is refusing mail from orange.fr (precisely smtp02.smtpout.orange.fr) because it has a poor reputation for sending SPAM.

Now I can not see it listed in any of the popular blocklists, but I have seen companies block all mail from other countries because all their business is national. Basically Orange is going to have to talk to the domain owner you are sending your mail to. ONLY Orange and the receiving domain can fix the issue.

Thanks Matt - will try and see what orange can do - however other email addresses in Australia do receive my emails and can forward them on. I hope they can sort this out - such a pain!!

Thunderbird gave the message to your provider. It is done. Your provider sent it to the recipients provider and they refused it and returned the Bad Reputation message. How do you see this as a Thunderbolt problem?

Hi Airmail - I am not implying it is a Thunderbird problem but trying to sort it out isn't simple and we have been using this email address and sending emails back and forth for over 10 years so it is hard for me to understand why this suddenly happens. But to reiterate, I am happy to understand it is not a T/B problem and you do answer questions very promptly that is more than can be said of Orange!