Why has my Thunderbird email suddenly stopped working, never happened before, when I went to sent an email, I got the following message: "Sending of the message failed. An error occurred while sending mail. The mail server responded: <cjants1@twcny.rr.com> sender rejected. The email address you are sending as must match the email address you used to auth. Please check your SMTP settings. AUP#Out-1500. Please verify that your email address is correct in your account settings and try again." I contacted mt email service, no problem. They said it was the 3rd party problem. I'm not a "techy". Pretty much computer illiterate. Need much help with situations. I also can not receive email, nothing works. It was working fine yesterday.