Mail from domino server has exceeded its message limit

I have my domino server relaying messages leaving my local internet domain to a host server. Inbound and outbound messages come through with no problems for a period of time then outbound messages begin to queue in the router and I need to restart the router to get them going again. The error message I receive in my Monitoring Results db is:

“Mail from ‘Domino server’ to destination ‘host server’ has exceeded its message limit.” then

“Router: Failed to connect to SMTP host ‘host server’ because Remote system no longer responding”

Am I missing a limit setting?