Not sure where to ask this question about the WP Hackers mailing list, so I thought I'd try here.
I joined the list about a month ago and get the posts to my gmail.com account no problem. However, whenever I try to post any replies or topics, I immediately get:
This is an automatically generated Delivery Status Notification
Delivery to the following recipient failed permanently:
Technical details of failure:
PERM_FAILURE: SMTP Error (state 13): 550 Administrative prohibition