javax.mail.MessagingException: Could not convert socket to TLS;
  nested exception is:
    java.net.SocketException: java.security.NoSuchAlgorithmException: Error constructing implementation (algorithm: Default, provider: SunJSSE, class: sun.security.ssl.SSLContextImpl$DefaultSSLContext)
    at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2140)
    at com.sun.mail.smtp.SMTPTransport$Authenticator.authenticate(SMTPTransport.java:917)
    at com.sun.mail.smtp.SMTPTransport.authenticate(SMTPTransport.java:858)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:762)
    at javax.mail.Service.connect(Service.java:342)
    at javax.mail.Service.connect(Service.java:222)
    at javax.mail.Service.connect(Service.java:243)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.net.SocketException: java.security.NoSuchAlgorithmException: Error constructing implementation (algorithm: Default, provider: SunJSSE, class: sun.security.ssl.SSLContextImpl$DefaultSSLContext)
    at java.base/javax.net.ssl.DefaultSSLSocketFactory.throwException(SSLSocketFactory.java:263)
    at java.base/javax.net.ssl.DefaultSSLSocketFactory.createSocket(SSLSocketFactory.java:285)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:528)
    at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2135)
    ... 12 more
Caused by: java.security.NoSuchAlgorithmException: Error constructing implementation (algorithm: Default, provider: SunJSSE, class: sun.security.ssl.SSLContextImpl$DefaultSSLContext)
    at java.base/java.security.Provider$Service.newInstance(Provider.java:1901)
    at java.base/sun.security.jca.GetInstance.getInstance(GetInstance.java:236)
    at java.base/sun.security.jca.GetInstance.getInstance(GetInstance.java:164)
    at java.base/javax.net.ssl.SSLContext.getInstance(SSLContext.java:168)
    at java.base/javax.net.ssl.SSLContext.getDefault(SSLContext.java:99)
    at java.base/javax.net.ssl.SSLSocketFactory.getDefault(SSLSocketFactory.java:123)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:523)
    ... 13 more
Caused by: java.security.KeyStoreException: problem accessing trust store
    at java.base/sun.security.ssl.TrustManagerFactoryImpl.engineInit(TrustManagerFactoryImpl.java:73)
    at java.base/javax.net.ssl.TrustManagerFactory.init(TrustManagerFactory.java:278)
    at java.base/sun.security.ssl.SSLContextImpl$DefaultManagersHolder.getTrustManagers(SSLContextImpl.java:1053)
    at java.base/sun.security.ssl.SSLContextImpl$DefaultManagersHolder.<clinit>(SSLContextImpl.java:1023)
    at java.base/sun.security.ssl.SSLContextImpl$DefaultSSLContext.<init>(SSLContextImpl.java:1198)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    at java.base/java.security.Provider.newInstanceUtil(Provider.java:154)
    at java.base/java.security.Provider$Service.newInstance(Provider.java:1894)
    at java.base/sun.security.jca.GetInstance.getInstance(GetInstance.java:236)
    at java.base/sun.security.jca.GetInstance.getInstance(GetInstance.java:164)
    at java.base/javax.net.ssl.SSLContext.getInstance(SSLContext.java:168)
    at java.base/javax.net.ssl.SSLContext.getDefault(SSLContext.java:99)
    at java.base/javax.net.ssl.SSLSocketFactory.getDefault(SSLSocketFactory.java:123)
    at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:523)
    at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2135)
    at com.sun.mail.smtp.SMTPTransport$Authenticator.authenticate(SMTPTransport.java:917)
    at com.sun.mail.smtp.SMTPTransport.authenticate(SMTPTransport.java:858)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:762)
    at javax.mail.Service.connect(Service.java:342)
    at javax.mail.Service.connect(Service.java:222)
    at javax.mail.Service.connect(Service.java:243)
    ... 4 more
Caused by: java.io.IOException: DerInputStream.getLength(): lengthTag=109, too big.
    at java.base/sun.security.util.DerInputStream.getLength(DerInputStream.java:606)
    at java.base/sun.security.util.DerValue.init(DerValue.java:390)
    at java.base/sun.security.util.DerValue.<init>(DerValue.java:331)
    at java.base/sun.security.util.DerValue.<init>(DerValue.java:344)
    at java.base/sun.security.pkcs12.PKCS12KeyStore.engineLoad(PKCS12KeyStore.java:1973)
    at java.base/sun.security.util.KeyStoreDelegator.engineLoad(KeyStoreDelegator.java:222)
    at java.base/java.security.KeyStore.load(KeyStore.java:1479)
    at java.base/sun.security.ssl.TrustStoreManager$TrustAnchorManager.loadKeyStore(TrustStoreManager.java:365)
    at java.base/sun.security.ssl.TrustStoreManager$TrustAnchorManager.getTrustedCerts(TrustStoreManager.java:313)
    at java.base/sun.security.ssl.TrustStoreManager.getTrustedCerts(TrustStoreManager.java:55)
    at java.base/sun.security.ssl.TrustManagerFactoryImpl.engineInit(TrustManagerFactoryImpl.java:49)
    ... 29 more
DEBUG SMTP: AUTH LOGIN failed

代码中添加

static {
    Security.removeProvider("SunEC");
}