[qmailtoaster] warning: trouble opening remote

[Stanley Robins]

hello,

i am getting these errors in Qmail send log.. what should be the cause ????

2006-04-21 13:12:04.145325500 warning: trouble opening remote/20/164792; will try again later
2006-04-21 13:12:00.145290500 warning: trouble opening remote/19/164607; will try again later
2006-04-21 13:12:00.145338500 warning: trouble opening remote/14/165200; will try again later
2006-04-21 13:12:00.145356500 warning: trouble opening remote/15/165454; will try again later
2006-04-21 13:12:00.145376500 warning: trouble opening remote/17/164674; will try again later
2006-04-21 13:12:00.145393500 warning: trouble opening remote/17/164697; will try again later
2006-04-21 13:12:00.145409500 warning: trouble opening remote/7/165308; will try again later
2006-04-21 13:12:04.145325500 warning: trouble opening remote/20/164792; will try again later
2006-04-21 13:12:04.145372500 warning: trouble opening remote/20/164815; will try again later