Email sending prob?

Question

One of my users is trying to send email to an outside company (changed to THEIRDOMAIN below) but they get the following error message:

The following recipient(s) could not be reached:

[e-mail] on 21/08/2007 15:38

you do not have permission to send to this recipient. For assistance contact you system administrator

<mail.OURDOMAIN.co.uk #5.7.1 smtp;501 5.7.1 this system is not configured to reply mail (r) from

<[e-mail]> to <[e-mail]> for US01.gotadsl.co.uk>

Can someone point me in the right direction?

Cheers

Answer 1

his email account  has been effectively blacklisted by system administrator