in log4j-jakarta-smtp/src/main/java/org/apache/logging/log4j/smtp/appender/SmtpManager.java [307:315]
protected void sendMultipartMessage(final MimeMessage msg, final MimeMultipart mp, final String subject)
throws MessagingException {
synchronized (msg) {
msg.setContent(mp);
msg.setSentDate(new Date());
msg.setSubject(subject);
Transport.send(msg);
}
}