I received an error message while sending a SMTP email with Thunderbird
I received an error message while sending a SMTP email with Thunderbird (18.104.22.168). It says “An error occurred while sending mail. The mail server responded: Authentication required. Please verify that your email address is correct in your Mail preferences and try again”.
After getting this message I turned off Avast outgoing mail checker. It was ok. But Avast sent me a warning message that I should not do it again. How can I fix this issue?
Please suggest me.