Connection reset by Alert in Mirth - mirth

Question

I am trying to set up an alert for a channel to send emails. The problem is that when a channel produces an alert, on having tried to send e-mail the mistake takes place: "Connection reset". The server of mail is external to the company.
To prove the sending of message in Mirth, I have defined a channel that when it receives a hl7 message sends a mail to a certain direction with the following code javascript:
var smtpConn = SMTPConnectionFactory.createSMTPConnection();
smtpConn.send('example1#mailserver.es', '', 'example2#mailserver.es', 'subject', 'body');
logger.info('mensaje enviado');
Producing the same mistake:
Caused by: javax.mail.MessagingException: Exception reading response;
nested exception is:
java.net.SocketException: Connection reset
at com.sun.mail.smtp.SMTPTransport.readServerResponse(SMTPTransport.java:1925)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1684)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:525)
at javax.mail.Service.connect(Service.java:313)
at javax.mail.Service.connect(Service.java:172)
at javax.mail.Service.connect(Service.java:121)
at javax.mail.Transport.send0(Transport.java:190)
at javax.mail.Transport.send(Transport.java:120)
at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1232)
The Setting configuration is:
SMTP Host: ipsmtphostserver, Port: 465,SendTimeOut:2000,DefaultFromAccess:anyemail#mail.com, SecureConnection:I have tried with both TTL and SSL,RequiereAuthentication: Yes.
I have thought that the problem was firewall or antivirus, but I have deactivated a moment them and it follows the problem.