Apache Ant sendet Mail nicht

<project name="LearningAnt" >  
   <target name="mail2work">  
      <mail mailhost="smtp.web.de" user="xyz@web.de" password="superpassword" mailport="587" ssl="true" enableStartTLS="true" encoding="mime" messagemimetype="text/html" subject="Test">  
         <from address="xyz@web.de"/>  
         <to address="abc@bla.com"/>  
         <message>This is a test message created by ANT</message>
      </mail>
   </target>
</project>

>ant mail2work -verbose
Apache Ant(TM) version 1.9.6 compiled on June 29 2015
Trying the default build file: build.xml
Buildfile: ...\build.xml
Detected Java version: 1.8 in: C:\Program Files\Java\jdk1.8.0_72\jre
Detected OS: Windows 7
parsing buildfile ...\build.xml with URI = file:.../build.xml
Project base dir set to: ...
Build sequence for target(s) `mail2work' is [mail2work]  
Complete build sequence is [mail2work, main, mail2web.de, ]

mail2work:
parsing buildfile jar:file:/T:/ant/lib/ant.jar!/org/apache/tools/ant/antlib.xml with URI = jar:file:/T:/ant/lib/ant.jar!
/org/apache/tools/ant/antlib.xml from a zip file
     [mail] Using MIME mail
     [mail] Sending email: Test
     [mail] From xyz@web.de
     [mail] ReplyTo 
     [mail] To [abc@bla.com]
     [mail] Cc 
     [mail] Bcc 
     [mail] Failed to send email: Exception reading response

BUILD FAILED
...\build.xml:34: Problem while sending mime mail:
        at org.apache.tools.ant.taskdefs.email.MimeMailer.send(MimeMailer.java:284)
        at org.apache.tools.ant.taskdefs.email.EmailTask.execute(EmailTask.java:575)
        at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:293)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
...........................