I have a gmail account and set up auto forwarding for many emails to Newsblur. All of a sudden I started receiving the below error message this morning (I blocked out the newsbulur email address below).
Your message couldn’t be delivered to XXXX@newsletters.newsblur.com because the remote server is misconfigured. See technical details below for more information.
The response from the remote server was:
550 5.7.1 Relaying denied