When attempting to log in to Horde webmail, you see the following error:
Error connecting to mail server.
You are unable to telnet localhost on port 143:
# telnet localhost 143
telnet: localhost: Name or service not known
localhost: Unknown host
127.0.0.1 localhostentry is missing in the
Name Service Switch misconfiguration.
127.0.0.1 localhostentry to the
/etc/nsswitch.conffile, making sure that there are no duplicate entries for the
hostsservice (there is only one line that describes the hosts):
~#grep hosts /etc/nsswitch.conf
#hosts: db files nisplus nis dns
hosts: files dns
Please also refer to the following article, which describes the similar issue: