Error Horde :: code: 535, response: Incorrect authentication data

Error while sending mail through Horde.

There was an error sending your message: authentication failure [SMTP: Invalid response code received from server (code: 535, response: Incorrect authentication data)]

I am using cPanel for this server and Horde as the email interface and found that I was getting error while sending mail from an email account. On investigation, I have found that the ownership of etc/ was incorrect; I correct it and the error was fixed.

Correct ownerships for the 'etc' and 'mail' folders are as below:

etc (all files and sub-folders):
User: Actual username
Group: mail

command to fix the ownership:

#  chown username.mail etc/ -R

(Here username is the actual domain username)

mail (all files and sub-folders):
User: Actual username
Group: Actual username

command to fix the ownership:

#  chown username.username mail/ -R

(Here username is the actual domain username)