Unable to deliver the message due to communication failure

[rosette76]

Error Message :
The following recipient(s) could not be reached
Unable to deliver the message due to a communication failure The
MTS-ID of the original message is: ......

* We receive this message only when we send to more than 3 external
addresses at the same time. If we send individual message we don't
have any error message.

* We don't have this problem with internal addresses

* We are running MS Exchange 5.5 SP4 on Windows NT
Please Help

 

[rdroske]

Maybe very slow DNS? Does it happen if all three are going to the same address?

 

[rosette76]

Yes, it's happening if I send it to the same address
I tried to do an nslookup -type=mx on many servers and it'S all working fine but we can't sent to more than 3 external recipients

 

[spambakian]

We've experienced this problem, but the To: line had about 30 addresses in it. The problem was that there were over 254 characters in the To: and CC: lines combined (Microsoft KB 180414). The user ended up creating a persoanl distribution list with all the addresses contained within it.