I have a client who complains that one of their own clients cannot send mail to them. The sender has performed a simple SMTP transmission and receives the following error:
SMTP Error 4570: Illegal response to the sender(550): 550 5.7.1 H:MXB<<SMTP client IP>>Connection refused to due abuse I realize this is a generic MTA question but I figured some may want to comment since it may be a spam abuse issue. I have gone to dnsstuff.com and checked the sender IP and all is well. PM
