This is a strange problem. One domain on my vps has problems with emails. The rest, using the same script, do not. I made 1 change right before it started. I was getting huge log files, so I tried to implement the log4j fix - had a problem with wrong version of files, so had to restore from backups, then my hosting provider made the fix for me.
Now no emails go out, just for this one domain, and the error log is full of these:
09/29/2018 19:25:15 org.apache.catalina.loader.ParallelWebappClassLoader.hasLoggingConfig()Z
org.apache.catalina.loader.ParallelWebappClassLoader.hasLoggingConfig()Z
java.lang.AbstractMethodError: org.apache.catalina.loader.ParallelWebappClassLoader.hasLoggingConfig()Z
at org.apache.juli.ClassLoaderLogManager.readConfiguration(ClassLoaderLogManager.java:456)
at org.apache.juli.ClassLoaderLogManager$3.run(ClassLoaderLogManager.java:429)
at org.apache.juli.ClassLoaderLogManager$3.run(ClassLoaderLogManager.java:425)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.juli.ClassLoaderLogManager.getClassLoaderInfo(ClassLoaderLogManager.java:425)
at org.apache.juli.ClassLoaderLogManager.getLogger(ClassLoaderLogManager.java:250)
at java.util.logging.LogManager.demandLogger(LogManager.java:551)
at java.util.logging.Logger.demandLogger(Logger.java:455)
at java.util.logging.Logger.getLogger(Logger.java:502)
at com.sun.mail.util.MailLogger.(MailLogger.java:104)
at javax.mail.Session.initLogger(Session.java:227)
at javax.mail.Session.(Session.java:212)
at javax.mail.Session.getInstance(Session.java:248)
at lucee.runtime.net.smtp.SMTPConnectionPool.createSession(SMTPConnectionPool.java:157)
at lucee.runtime.net.smtp.SMTPConnectionPool.access$200(SMTPConnectionPool.java:37)
at lucee.runtime.net.smtp.SMTPConnectionPool$SessionAndTransport.(SMTPConnectionPool.java:183)
at lucee.runtime.net.smtp.SMTPConnectionPool.getSessionAndTransport(SMTPConnectionPool.java:57)
at lucee.runtime.net.smtp.SMTPClient.createMimeMessage(SMTPClient.java:456)
at lucee.runtime.net.smtp.SMTPClient._send(SMTPClient.java:827)
at lucee.runtime.spooler.mail.MailSpoolerTask.execute(MailSpoolerTask.java:124)
at lucee.runtime.spooler.SpoolerTaskSupport._execute(SpoolerTaskSupport.java:103)
at lucee.runtime.spooler.SpoolerEngineImpl.execute(SpoolerEngineImpl.java:604)
at lucee.runtime.spooler.SpoolerEngineImpl$TaskThread.run(SpoolerEngineImpl.java:539)