retour des envois mail aux mêmes adresses reçuesr : Undelivred Mail return to Sender ?

Please use English. You can use Google Translate if your English is not good. '''Question Translation:''' '''Email delivery failures to the same addresses: "Undelivered Mail – Return to Sender"?''' '''What should I do to resolve this issue for all my replies to the email I received?''' This is not a Thunderbird problem. What I means is, thunderbird is not creating the issue, so you can rest assured all is ok. The server has sent you an email telling you that email could not be delivered. Usually the email offers a bit more information but these are the more common reasons for a return to sender. 1. Email address does not exist - it may be badly formatted or a typo error - suggest you check for typo errors. 2.Email address did exist but has now been deactivated, so it's correctly spelt but a dead account. 3. Email address does exist but the person has used up all their quota; mailbox is full, so server cannot accept any more mail until some space has been created. 4. Email rejected by server because it failed the server spam filter 5. Server has a temporary issue. 6. Email doesn’t comply with the authentication policies of the sending domain eg: rejected due to DMARC 5 Blocked - your email address or IP address has been put on a block list. Suggest you check this using this link: https://check.spamhaus.org/