Error: Cannot retrieve repository metadata (repomd.xml) for repository

< SKIP > Function: check_new_iredmail.
< INFO > Preparing yum repositories ...
< INFO > Installing package(s): epel-release
Loaded plugins: refresh-packagekit, rhnplugin
Repository 'Yum-Server' is missing name in configuration, using id
This system is not registered with RHN.
RHN support will be disabled.
Yum-Server                                               | 1.3 kB     00:00
Yum-Server/primary                                       | 1.6 MB     00:00
Yum-Server                                                            3431/3431
iRedMail                                                 | 2.9 kB     00:00
iRedMail/primary_db                                      |  91 kB     00:01
Error: Cannot retrieve repository metadata (repomd.xml) for repository: tmp_epel. Please verify its path and try again
< ERROR > Installation failed, please check the terminal output.
< ERROR > If you're not sure what the problem is, try to get help in iRedMail
< ERROR > forum: http://www.iredmail.org/forum/