troubleshooting Question

Unable to send from Exchange 2010 to Exchange 2003 Coexistence mode

Avatar of Sean Gaughan
Sean Gaughan asked on
10 Comments3 Solutions126 ViewsLast Modified:
I get the error:

 "451.4.4.0 Primary target IP address responded with 421.4.4.2 Connection dropped due to SocketError"

I am able to send from 2003 to 2010, and from 2010 to internet email addresses and back again however the only route that doesnt work is from 2010 to 2003.

I have created a bidirectional RGC but still the same error appears. Googling this issue only leads to dead ends.

I would massively appreciate it if anyone could help!
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