BMgr 3.6 sp2a on nw50sp6a

groupwise 5.5 sp5 on nw50sp6a

i know mail proxy is buggy but in the last month things have gotten much
worse than normal.

currently i am getting "SMTP Proxy failed to connect to internal mail
server for incoming mail" on the BMgr server about 100 perday. and i
have received misc. reports of mail being rejected.

i would like to continue using mail proxy.

suggestions on where to start with this?
is there a log file i can look in that will give more info on this error?