When hitting the following error messages, JIRA doesn't seems attaching the file and remove the file from the tmp directory.

2008-04-04 10:40:34,079 JiraQuartzScheduler_Worker-2 WARN [jira.issue.managers.DefaultAttachmentManager] Cannot create attachment without a filename - inline content? See http://jira.atlassian.com/browse/JRA-10825 (file=tempattach22592dat).
2008-04-04 10:40:34,735 JiraQuartzScheduler_Worker-2 WARN [jira.issue.managers.DefaultAttachmentManager] Cannot create attachment without a filename - inline content? See http://jira.atlassian.com/browse/JRA-10825 (file=tempattach22593dat).

Hence, the size of the tmp directory is growing.

Steps to reproduce the problem:

1. Compose an new email with .txt attachment file and send to mail server.
2. JIRA will created an new issue for example KA-241.
3. Try forward the email with .txt attachment file and add a new comment for the first time.
4. Try forward the email with .txt attachment file and add another comment for the second time.
5. JIRA log will shown the following warning message:

   2013-08-21 17:36:17,497 QuartzScheduler_Worker-2 WARN ServiceRunner    Testing [jira.issue.managers.DefaultAttachmentManager] Cannot create attachment without a filename - inline content? See http://jira.atlassian.com/browse/JRA-10825 (file=tempattach4407109991392688009dat).