Error: A communications failure or interuption was encountered, - IOException (4288603)

Occassionally there are some intermittent NDRs generated that appear back in Exchange where mail can not be delivered to the Notes/Domino system.

See the NDR.jpg for a sample.

See Error.jpg for the full error message

This was casued by the Availability Index of the Domino Hub servers being extremely low. One of the servers was showing 0% and the other was showing 12%

A typically healthy Domino server should be in the region of 80%-100%. Even a busy, overloaded server might drop to 50-65%.

A reboot of the hub server should have resolved the Availability issue. However in this instance there were insufficient system resources resulting in an almost immediate drop to 0% within 5 minutes of rebooting the hub.

To resolve this issue the Domino server needed to be better resourced. Highlight the drop in the System Availability to the Domino Administrator as the server may have not been sized/optimized correctly for the environment.