Hi,

Which version of Thunderbird are you using ? Check if you can update it.

Thunderbird or an add-on is adding bare line feed to your message and the recipient server can't deal with it. Modern mail application remove it by default. That's why it's working from web application.

Many thanks for your reply totti.

I have just updated to Thunderbird 102.1.2 but still have the problem.

The weird thing is that I can send the same 1 word email to 100 different addresses but it is always the same 2 addresses that are undeliverable. In the last 15 years I have never had a problem with these 2 emails so a bug has appeared in the system somehow. Is there any way of clearing or resetting it? Thanks

I have the same problem.... i can also use webmail for outlook.com and it goes thru, so what is in theThunderbird client that i need to change???? This started a week ago.

The mail client submitted this message with bare line feeds, which cannot be sent via SMTP protocol DATA command and receiving system does not support BDAT.

Joan

I have the same problem? This is the message I get:

Delivery has failed to these recipients or groups: [the email it couldn't send message to is shown here] The mail client submitted this message with bare line feeds, which cannot be sent via SMTP protocol DATA command and receiving system does not support BDAT.

The email I use to send the undeliverable messages is a '@hotmail.com' address. Any assistance on how to correct this would be greatly appreciated

Bernie