How to overcome the limitations for "Cannot send mail: Sender Address Blocked"

How to overcome the limitations for "Cannot send mail: Sender Address Blocked"

Hi there,
  • Unable to send any email using this account: noreply@petsbandu.com
    • Can you please unblock it?
  • Is there a limit on how much amount of email can my account send per day?
    • Is the limitation in the in number of emails or the size of the emails sent per day?
    • What do I need to do to overcome that limitation?
Thanks.