I have configured a roundcube webmail with roundcube 1.6.6. I have a couple of email servers which is configured with postfix and dovecot like mx1.example.com, mx2.example.com and mx3.example.com. (Sorry, i cant mention the real host names). I am able to login to the webmail with the email account of any of these mail servers and also can receive the mails. But when i try to send emails from webmail, it shows the below error.
SMTP error (554): Recipient "Email" cannot be added (5.7.1 <unknown[IP]>: Client host rejected: Access denied).
Any idea what could be wrong here.
