[exim] Random problem

I'm facing random problems with a provider of our company. The send two
well types of emails. One of them arrives well, but the other always
bounce.

My log just said.
2004-11-11 10:05:11 1CSFUO-0001bc-HZ SMTP data timeout (message
abandoned) on connection from roy.internetsecure.com [66.46.151.132]

But, its log said
----- Transcript of session follows -----
<320is@???>... Deferred: Bad file descriptor
Warning: message still undelivered after 4 hours
Will keep trying until message is 4 days old

I've enabled more fields in log selector, but only see the SMTP data
timeout.

And, don't know what means 'Deferred: Bad file descriptor', is this
message generated by my exim or by their mail server ?

Does 'Bad file descriptor' have to do anything with a socket closed ?

Regards
mike