announcement-mail fails if server implements GreyListing : 451 Greylisted

Our mail server implements Greylisting (see http://postgrey.schweikert.ch/help/ or http://en.wikipedia.org/wiki/Greylisting), the announcement-mail goal fails with this message :

[INFO] ------------------------------------------------------------------------
[INFO] Building base
[INFO] task-segment: [changes:announcement-mail]
[INFO] ------------------------------------------------------------------------
[INFO] Preparing changes:announcement-mail
[INFO] [changes:announcement-generate]
[INFO] Creating announcement file from ./src/changes/changes.xml...
[INFO] Created template ./target/announcement/announcement.vm
[INFO] [changes:announcement-mail]
[INFO] Connecting to Host: mailhost.lan:25
[INFO] Using this sender for email announcement: test@mailhost.lan < test >
[INFO] Sending mail to test2@mailhost.lan...
DEBUG: JavaMail version 1.4ea
DEBUG: java.io.FileNotFoundException: /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/javamail.providers (No such file or directory)
DEBUG: !anyLoaded
DEBUG: not loading resource: /META-INF/javamail.providers
DEBUG: successfully loaded resource: /META-INF/javamail.default.providers
DEBUG: Tables of loaded providers
DEBUG: Providers Listed By Class Name:

{com.sun.mail.smtp.SMTPSSLTransport=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Sun Microsystems, Inc], com.sun.mail.smtp.SMTPTransport=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc], com.sun.mail.imap.IMAPSSLStore=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Sun Microsystems, Inc], com.sun.mail.pop3.POP3SSLStore=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Sun Microsystems, Inc], com.sun.mail.imap.IMAPStore=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], com.sun.mail.pop3.POP3Store=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc]}

DEBUG: Providers Listed By Protocol:

{imaps=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Sun Microsystems, Inc], imap=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], smtps=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Sun Microsystems, Inc], pop3=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc], pop3s=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Sun Microsystems, Inc], smtp=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]}

DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
DEBUG: !anyLoaded
DEBUG: not loading resource: /META-INF/javamail.address.map
DEBUG: java.io.FileNotFoundException: /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/javamail.address.map (No such file or directory)
DEBUG: setDebug: JavaMail version 1.4ea
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth false
DEBUG SMTP: trying to connect to host "mailhost.lan", port 25, isSSL false
220 mailhost.lan ESMTP Exim 4.68 Tue, 19 Feb 2008 11:31:44 +0100
DEBUG SMTP: connected to host "mailhost.lan", port: 25

EHLO pc-test
250-mailhost.lan Hello pc-test [10.143.90.8]
250-SIZE 52428800
250-PIPELINING
250-STARTTLS
250 HELP
DEBUG SMTP: Found extension "SIZE", arg "52428800"
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "HELP", arg ""
DEBUG SMTP: use8bit false
MAIL FROM:<test@mailhost.lan>
250 OK
RCPT TO:<test2@mailhost.lan>
451 Greylisted, see http://postgrey.schweikert.ch/help
DEBUG SMTP: Valid Unsent Addresses
DEBUG SMTP: test2@mailhost.lan
DEBUG SMTP: Sending failed because of invalid destination addresses
RSET
250 Reset OK
javax.mail.SendFailedException: Invalid Addresses;
nested exception is:
com.sun.mail.smtp.SMTPAddressFailedException: 451 Greylisted, see http://postgrey.schweikert.ch/help

at com.sun.mail.smtp.SMTPTransport.rcptTo(SMTPTransport.java:1196)
at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:584)
at javax.mail.Transport.send0(Transport.java:169)
at javax.mail.Transport.send(Transport.java:98)
at org.apache.maven.plugin.announcement.mailsender.ProjectJavamailMailSender.send(ProjectJavamailMailSender.java:193)
at org.codehaus.plexus.mailsender.AbstractMailSender.send(AbstractMailSender.java:144)
at org.codehaus.plexus.mailsender.AbstractMailSender.send(AbstractMailSender.java:120)
at org.apache.maven.plugin.announcement.AnnouncementMailMojo.sendMessage(AnnouncementMailMojo.java:226)
at org.apache.maven.plugin.announcement.AnnouncementMailMojo.execute(AnnouncementMailMojo.java:193)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:447)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:539)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:493)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:463)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:311)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:278)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:143)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:333)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:126)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:282)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: com.sun.mail.smtp.SMTPAddressFailedException: 451 Greylisted, see http://postgrey.schweikert.ch/help
at com.sun.mail.smtp.SMTPTransport.rcptTo(SMTPTransport.java:1061)
... 26 more
QUIT
221 mailhost.lan closing connection
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to send email < test2@mailhost.lan >

Embedded error: Error while sending mail.
451 Greylisted, see http://postgrey.schweikert.ch/help