Exchange mail delivery issue
Posted on 2014-02-18
I have a strange error within Exchange...
Users cannot send to a number of different domains (that we've been able to send to for years) and the messages are just sitting in the queue on Exchange
The "last error" text shows
451 4.4.0 Primary target IP address responded with "421 please try later" attempted failover.....
I have checked our domain against blacklists and come up with nothing, though several have reported that our
Forward DNS does not match Reverse DNS - is this a problem?
I have also tried to telnet into the problem domains on port 25 and the connection gets immediately dropped with error "421 please try later"
I'm supposed to be on holiday tonight, any help gratefully received !!