Symptoms

If we have an E-mail server which allows anonymous usage, the we set mail.smtp.auth=false in the <confluence-install>/conf/server.xml.  However the setting does not appear to work and the following appears in the atlassian-confluence.log:

2013-04-09 11:44:00,095 ERROR [scheduler_Worker-1] [atlassian.core.task.AbstractErrorQueuedTaskQueue] handleException com.atlassian.mail.MailException: javax.mail.AuthenticationFailedException: failed to connect, no user name specified?
com.atlassian.mail.MailException: javax.mail.AuthenticationFailedException: failed to connect, no user name specified?
	at com.atlassian.mail.server.impl.SMTPMailServerImpl.send(SMTPMailServerImpl.java:193)
	at com.atlassian.confluence.jmx.JmxSMTPMailServer.send(JmxSMTPMailServer.java:80)

Cause

This is caused by a known bug which is tracked at  CONF-29000 - Getting issue details... STATUS

Resolution

1. Remove the mail server configuration
2. Create a new configuration, ensuring that no username or password (including whitespace) is saved at all.