I'm guessing that you have the correct settings in Thunderbird, but not in Mail. Without knowing what those setting might be, no one here can help you. Care to at least tell us which email service you are trying to use?
Before responding, you need to address this issue: ISPs routinely block SMTP servers on foreign domains. Most SMTP servers use Port 25. Many ISPs block only that port in an effort to block foreign SMTP access. Port 587 is also devoted to SMTP access. It is often not blocked. Try using Port 587 for SMTP access in Mail.