[IMail Forum] Intermittent Interuption

[Michael U]

What would cause IMail to randomly reject emails?  I have a user who is constantly complaining that he cannot send to certain domains.  Coincidentally, certain domains cannot send to him.  I checked ORDB.ORG and we are not on the list.  What can cause this?   As Always, Thanks in Advance.   Michael U - MCP Network Administrator