The tlsMode option specifies, how the TLS protection of the SMTP connection to the SMTP server is initiated.
tlsMode |
EXPLICIT | IMPLICIT |
EXPLICIT
If via the option tlsSecureConnection a TLS protection of the SMTP connection is requested, then this is initiated with the STARTTLS mechanism.
This is generally the setting to be used with submission to the SMTP server over port 25 or 587.
IMPLICIT
>If via the option tlsSecureConnection a TLS protection of the SMTP connection is requested, then this is performed directly after the TCP connection establishment to the SMTP server. There is not made a distinction between the tlsSecureConnection settings OPTIONAL and REQUIRED: if setting up the TLS protection fails, the SMTP connection is closed.
This is generally the setting to be used with submission to the SMTP server over port 465.