Message rejected error on some workstations

[ozejohn]

Hi,

We have a number of applications that send a series of emails when particular events are triggered. This runs fine on many workstations. On a few we get a message every now and again when a lot of emails are being sent. The log always looks as shown below :-

0 <71 < 220 xxx.mx.bigpond.com ESMTP server ready Tue, 30 Sep 2008 22:34:43 +0000
73 > HELO xxx.com.au
73 < 250 xxx.mx.bigpond.com
74 > MAIL FROM: <xxx>
74 < 250 Sender <xxx> Ok
75 > RCPT TO: <xxx>
75 < 250 Recipient <xxx> Ok
75 > RCPT TO: <xxx>
75 < 250 Recipient <xxx> Ok
76 > DATA
76 < 421 Message rejected

We suspect it is a timing thing about a lot of emails being sent quickly. But we are not sure. Does anyone have any suggestions on how we might chase this up.