I have a client that is getting a 550 error when sending email to some addresses. This looks like:
SMTP error from remote mail server after RCPT TO:<firstname.lastname@example.org>:
host mx3.netregistry.net [22.214.171.124]: 550-Verification failed for <email@example.com>
550 Sender verify failed
I've been through his email client and it is set up correctly with the out going SMTP mail correct.
I've also checked that the addresses he's sending to are correct.
Would anyone have any advice on how to correct this?