I've installed Thunderbird on another computer, it's connected because I'm getting messages on both, but when I try to send an email from the other one, I get the following message that the mail was not sent. This is the mail system at host relay1-d.mail.gandi.net. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message.