UnsupportedEncodingException when parsing email with utf-7 or unicode-1-1-utf-7 encoding

We are evaluating JIRA and got following error when an issue was submitted by email. This message gets repeatded and system keeps adding same issue again and again.
2005-02-01 13:47:14,335 ERROR [service.util.handler.CreateIssueHandler] Could not create issue!
java.io.UnsupportedEncodingException: utf-7
at sun.io.Converters.getConverterClass(Converters.java:215)
at sun.io.Converters.newConverter(Converters.java:248)
at sun.io.ByteToCharConverter.getConverter(ByteToCharConverter.java:64)
at sun.nio.cs.StreamDecoder$ConverterSD.<init>(StreamDecoder.java:223)
at sun.nio.cs.StreamDecoder$ConverterSD.<init>(StreamDecoder.java:209)
at sun.nio.cs.StreamDecoder.forInputStreamReader(StreamDecoder.java:76)
at java.io.InputStreamReader.<init>(InputStreamReader.java:83)
at com.sun.mail.handlers.text_plain.getContent(text_plain.java:65)
at javax.activation.DataSourceDataContentHandler.getContent(DataHandler.
java:755)
at javax.activation.DataHandler.getContent(DataHandler.java:511)
at javax.mail.internet.MimeMessage.getContent(MimeMessage.java:1259)
at com.atlassian.jira.service.util.handler.AbstractMessageHandler.create
AttachmentsForMessage(AbstractMessageHandler.java:111)
at com.atlassian.jira.service.util.handler.CreateIssueHandler.handleMess
age(CreateIssueHandler.java:136)
at com.atlassian.jira.service.util.handler.CreateOrCommentHandler.handle
Message(CreateOrCommentHandler.java:114)
at com.atlassian.jira.service.services.pop.PopService.run(PopService.jav
a:117)
at com.atlassian.jira.service.JiraServiceContainer.run(JiraServiceContai
ner.java:53)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:5
0)
at org.quartz.core.JobRunShell.run(JobRunShell.java:147)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.j
ava:387)
2005-02-01 13:48:37,920 ERROR [service.util.handler.CreateIssueHandler] Could no
t create issue!
java.io.UnsupportedEncodingException: utf-7
at sun.io.Converters.getConverterClass(Converters.java:215)
at sun.io.Converters.newConverter(Converters.java:248)
at sun.io.ByteToCharConverter.getConverter(ByteToCharConverter.java:64)
at sun.nio.cs.StreamDecoder$ConverterSD.<init>(StreamDecoder.java:223)
at sun.nio.cs.StreamDecoder$ConverterSD.<init>(StreamDecoder.java:209)
at sun.nio.cs.StreamDecoder.forInputStreamReader(StreamDecoder.java:76)
at java.io.InputStreamReader.<init>(InputStreamReader.java:83)
at com.sun.mail.handlers.text_plain.getContent(text_plain.java:65)
at javax.activation.DataSourceDataContentHandler.getContent(DataHandler.
java:755)
at javax.activation.DataHandler.getContent(DataHandler.java:511)
at javax.mail.internet.MimeMessage.getContent(MimeMessage.java:1259)
at com.atlassian.jira.service.util.handler.AbstractMessageHandler.create
AttachmentsForMessage(AbstractMessageHandler.java:111)
at com.atlassian.jira.service.util.handler.CreateIssueHandler.handleMess
age(CreateIssueHandler.java:136)
at com.atlassian.jira.service.util.handler.CreateOrCommentHandler.handle
Message(CreateOrCommentHandler.java:114)
at com.atlassian.jira.service.services.pop.PopService.run(PopService.jav
a:117)
at com.atlassian.jira.service.JiraServiceContainer.run(JiraServiceContai
ner.java:53)
at com.atlassian.jira.service.ServiceRunner.execute(ServiceRunner.java:5
0)
at org.quartz.core.JobRunShell.run(JobRunShell.java:147)
at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.j
ava:387)