Log4Net doesn't send e-mail - log4net-configuration

Question

This is configuration
<log4net debug="true">
<appender name="RFileAppender" type="log4net.Appender.RollingFileAppender, log4net">
<File value="logs/file.txt" />
<AppendToFile value="true" />
<DatePattern value="_yyyyMMdd" />
<RollingStyle value="Date" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level %date ==> %message%newline" />
</layout>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="RFileAppender" />
</root>
<appender name="SmtpAppender" type="log4net.Appender.SmtpAppender">
<to value="mail" />
<from value="mail" />
<subject value="Service Error Log" />
<smtpHost value="SMTPServer.domain.com" />
<bufferSize value="512" />
<lossy value="true" />
<evaluator type="log4net.Core.LevelEvaluator">
<threshold value="ERROR"/>
</evaluator>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%newline%date [%thread] %-5level %logger [%property{NDC}] - %message%newline%newline%newline" />
</layout>
</appender>
<root>
<level value="Error" />
<appender-ref ref="SmtpAppender" />
</root>
</log4net>
This is the method I use to send the email
private void SendErrorLogByMail(string error)
{
mailLogger.Error(error);
}
I think it is the configuration, maybe something is missing or some wrong data but I don't know what, what did I do wrong? I put two appenders because the info and warning log levels must be written in the file, while the error levels in both the file and the mail
UPDATE
<log4net debug="true">
<appender name="RFileAppender" type="log4net.Appender.RollingFileAppender, log4net">
<File value="log.txt"/>
<AppendToFile value="true"/>
<DatePattern value="_yyyyMMdd"/>
<RollingStyle value="Date"/>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level %date ==> %message%newline"/>
</layout>
</appender>
<root>
<level value="ALL"/>
<appender-ref ref="RFileAppender"/>
</root>
<appender name="SmtpAppender" type="log4net.Appender.SmtpAppender">
<to value="from" />
<from value="to" />
<subject value="Error Log" />
<bufferSize value="512" />
<smtpHost value="smtp.gmail.com" />
<port value="587" />
<authentication value="Basic" />
<username value="***" />
<password value="***" />
<lossy value="true" />
<evaluator type="log4net.Core.LevelEvaluator">
<threshold value="ERROR"/>
</evaluator>
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%newline%date [%thread] %-5level %logger [%property{NDC}] - %message%newline%newline%newline" />
</layout>
</appender>
<root>
<level value="Error" />
<appender-ref ref="SmtpAppender" />
</root>
</log4net>
Now when log4net is configured this error is returned:
log4net: ERROR [SmtpAppender] ErrorCode: GenericFailure. Error occurred while sending e-mail notification.
System.Net.Mail.SmtpException: The SMTP server requires a secure connection or the client has not been authenticated. Server response: 5.7.0 Must issue a STARTTLS command first. v18sm36645763edx.30 - gsmtp
in System.Net.Mail.MailCommand.CheckResponse (SmtpStatusCode statusCode, String response)
in System.Net.Mail.MailCommand.Send (SmtpConnection conn, Byte [] command, String from)
in System.Net.Mail.SmtpTransport.SendMail (MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException & exception)
in System.Net.Mail.SmtpClient.Send (MailMessage message)
in log4net.Appender.SmtpAppender.SendEmail (String messageBody)
in log4net.Appender.SmtpAppender.SendBuffer (LoggingEvent [] events)

Answer 1

Look. I'm just seeing your configuration and did you try to change tag value for another host, like Gmail?
I don't have experience with log4net but sometimes when something is wrong to send an email, probably can be the SMTP host, port.
Make senses ?