Plesk:: Login Failed (Unable to login to Horde Webmail)

While Login into Horde Webmail gives :Login failed error then follow the below steps to fix this problem:-
1) By command line using telnet please check if you are able to connect to localhost:143 from the command line using telnet and if you get the error as below:
# telnet localhost 143
localhost/143: Name or service not [...]