Plesk is one of the commonly using web hosting control panels. Here we discuss some SMTP settings in Plesk server. Some times we will face SMTP authentication issues, when we try to send mails via RoundCube SMTP authentication fails with SMTP Error
(250): Authentication failed. When we try to send mails from RoundCube you will receive a message in the roundcube interface as follows:
SMTP Error (250): Authentication failed
This occurs due to Incorrect authentication settings in Postfix: SMTP connections over SSL or TLS is enabled instead of password authentication.
This can be fixed by commenting a set of lines from the file “/etc/postfix/main.cf“.
Open the file /etc/postfix/main.cf find out the below set of lines and comment it.
# smtpd_tls_protocols = SSLv3, TLSv1 # smtpd_tls_ciphers = medium # smtpd_tls_exclude_ciphers = aNULL # smtpd_sasl_security_options = noplaintext # smtpd_tls_auth_only = yes # tls_ssl_options = NO_COMPRESSION
Now you can restart postfix and try sending mails from RoundCube.