public Session getMailSession()

in commons-email2-javax/src/main/java/org/apache/commons/mail2/javax/Email.java [800:853]
40 lines of code
11 McCabe index (conditional complexity)

    public Session getMailSession() throws EmailException {
        if (session == null) {
            final Properties properties = new Properties(System.getProperties());
            properties.setProperty(EmailConstants.MAIL_TRANSPORT_PROTOCOL, EmailConstants.SMTP);

            if (EmailUtils.isEmpty(hostName)) {
                hostName = properties.getProperty(EmailConstants.MAIL_HOST);
            }

            EmailException.checkNonEmpty(hostName, () -> "Cannot find valid hostname for mail session");

            properties.setProperty(EmailConstants.MAIL_PORT, smtpPort);
            properties.setProperty(EmailConstants.MAIL_HOST, hostName);
            properties.setProperty(EmailConstants.MAIL_DEBUG, String.valueOf(debug));

            properties.setProperty(EmailConstants.MAIL_TRANSPORT_STARTTLS_ENABLE, Boolean.toString(isStartTLSEnabled()));
            properties.setProperty(EmailConstants.MAIL_TRANSPORT_STARTTLS_REQUIRED, Boolean.toString(isStartTLSRequired()));

            properties.setProperty(EmailConstants.MAIL_SMTP_SEND_PARTIAL, Boolean.toString(isSendPartial()));
            properties.setProperty(EmailConstants.MAIL_SMTPS_SEND_PARTIAL, Boolean.toString(isSendPartial()));

            if (authenticator != null) {
                properties.setProperty(EmailConstants.MAIL_SMTP_AUTH, "true");
            }

            if (isSSLOnConnect()) {
                properties.setProperty(EmailConstants.MAIL_PORT, sslSmtpPort);
                properties.setProperty(EmailConstants.MAIL_SMTP_SOCKET_FACTORY_PORT, sslSmtpPort);
                properties.setProperty(EmailConstants.MAIL_SMTP_SOCKET_FACTORY_CLASS, "javax.net.ssl.SSLSocketFactory");
                properties.setProperty(EmailConstants.MAIL_SMTP_SOCKET_FACTORY_FALLBACK, "false");
            }

            if ((isSSLOnConnect() || isStartTLSEnabled()) && isSSLCheckServerIdentity()) {
                properties.setProperty(EmailConstants.MAIL_SMTP_SSL_CHECKSERVERIDENTITY, "true");
            }

            if (bounceAddress != null) {
                properties.setProperty(EmailConstants.MAIL_SMTP_FROM, bounceAddress);
            }

            if (socketTimeout > 0) {
                properties.setProperty(EmailConstants.MAIL_SMTP_TIMEOUT, Integer.toString(socketTimeout));
            }

            if (socketConnectionTimeout > 0) {
                properties.setProperty(EmailConstants.MAIL_SMTP_CONNECTIONTIMEOUT, Integer.toString(socketConnectionTimeout));
            }

            // changed this (back) to getInstance due to security exceptions
            // caused when testing using Maven
            session = Session.getInstance(properties, authenticator);
        }
        return session;
    }