The error could mean that you don’t have smtp_sasl_auth_enable = yes in your postfix conf. what is the output of postconf -n does it contain the above string? if not, then please uncomment or edit /etc/postfix/main.cf and report back.
The error could mean that you don’t have smtp_sasl_auth_enable = yes in your postfix conf. what is the output of postconf -n does it contain the above string? if not, then please uncomment or edit /etc/postfix/main.cf and report back.