Why satellite-sync fails with space error even if have free space available?

Issue

• Satellite-sync fails with the following error:

Importing:  +++ sending log as an email +++
+++ sending log as an email +++
Traceback (most recent call last):
  File "/usr/bin/satellite-sync", line 176, in <module>
    systemExit_exception(7, "SYNC ERROR: attempting to display as much information as possible:", e)
  File "/usr/bin/satellite-sync", line 126, in systemExit_exception
    satsync.sendMail(forceEmail=1)
  File "/usr/lib/python2.6/site-packages/spacewalk/satellite_tools/satsync.py", line 376, in sendMail
    rhnMail.send(headers, body, sender=sndr)
  File "/usr/lib/python2.6/site-packages/spacewalk/common/rhnMail.py", line 55, in send
    server = smtplib.SMTP('localhost')
  File "/usr/lib64/python2.6/smtplib.py", line 239, in __init__
    (code, msg) = self.connect(host, port)
  File "/usr/lib64/python2.6/smtplib.py", line 295, in connect
    self.sock = self._get_socket(host, port, self.timeout)
  File "/usr/lib64/python2.6/smtplib.py", line 273, in _get_socket
    return socket.create_connection((port, host), timeout)
  File "/usr/lib64/python2.6/socket.py", line 567, in create_connection
    raise error, msg
socket.error: [Errno 97] Address family not supported by protocol