Help ! "Error getting results from LDAP in map ldapmra:"

[Lynn Harden]

I run XP Pro, I have Symantec Internet Security 2004 installed.
Occasionally (and this morning - continually) I get a Symantec proxy error
as follows:

"Your email message was unable to be sent because your mail server rejected
the sender.
451 4.3.5 Error getting LDAP results in map ldapmra: Can't contact LDAP
server"

Can anyone clarify what on earth this is about please. I can't find anything
appropriate on the MS site or the Symantec site - and since the message
doesn;t indicate *which* of a bunch of email sent, is the problem email,
it's causing me grief.

Thanks