Horde webmail giving is error while sending mail.
There was an error sending your message: Failed to add recipient: firstname.lastname@example.org [SMTP: Invalid response code received from server (code: 550, response: Verification failed for <email@example.com> No Such User Here Sender verify failed)]
I am getting this error for this domain only all other existing domains are working fine in horde webmail.
1 thing i have noticed which is : <firstname.lastname@example.org>
While i have logged in using email@example.com
mail id then why this mail id <firstname.lastname@example.org> is showing in horde webmail