My provider uses unencrypted transmission of data... But: finally I found the solution: the right line is not auth on but auth login "Auth on" leaves to msmtp to find the most sicure method, so it thinks that LOGIN is not sicure and doesn't send... With le right line, I force msmtp to use the LOGIN method. I tried Sendmail with Slackware, now Exim end msmtp. Yes, now it's time to try Postfix too... Thanx to both you M. PS Yes, I'm using SID