commons-email-1.4.jar
javax.mail-1.5.2.jar

public class mail {
    public static void main(String[] args)  {
        MultiPartEmail  mail = new MultiPartEmail ();
        mail.setHostName("192.168.10.30");
        mail.setAuthentication("test@hongtiantao.com", "fhAS");
        mail.setCharset("UTF-8");
        try {
            mail.setFrom("test@hongtiantao.com", "红天桃客户服务");
            mail.addTo("179630791@qq.com","Chrome");
            mail.setSubject("待办事务提醒");
            mail.setMsg("A" + "有一条新记录" + "Z" + "等待审核");
            mail.setStartTLSEnabled(true);
            mail.setSmtpPort(587);
            mail.send();
        } catch (EmailException e) {
            e.printStackTrace();
        }

    }

DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "SIZE", arg "15728640"
DEBUG SMTP: Found extension "ETRN", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "DSN", arg ""
STARTTLS
220 2.0.0 Ready to start TLS
javax.mail.MessagingException: Could not convert socket to TLS;
  nested exception is:
    javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2155)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:752)
    at javax.mail.Service.connect(Service.java:366)
    at javax.mail.Service.connect(Service.java:246)
    at EmailTest.main(EmailTest.java:42)
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1884)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:276)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:270)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1439)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:209)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:878)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:814)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1016)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1312)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1339)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1323)
    at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:626)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:553)
    at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2150)
    ... 4 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:385)
    at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
    at sun.security.validator.Validator.validate(Validator.java:260)
    at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:326)
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:126)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1421)
    ... 14 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:196)
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:268)
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:380)
    ... 20 more

JDK1.7无法运行，报错为PKIX：unable to find valid certification path to requested target，更换1.8后正常运行。

更换后报错
java.lang.RuntimeException: java.io.IOException: invalid constant type: 15，需单独指定javassist 包版本，升级为3.20.0-GA问题解决。