Hi, This is a non delivery report from someone outside our organisation to someone in our domain. Normally mail comes through, except a couple of times. This message is generated by Mailer-Deamon@sendersdomain.invalid We have a SBS 2003 with exchange 2003. mailbackup.telenet-ops.be is a mailbackupserver at our provider. I noticed that our internet connection sometimes is gone for a few seconds (didn't find a solution for that yet), so this backup should take over. Something tells me the backup server is not configured correctly by our provider? Is that correct? Thanks in advance. Regards, Vincent This message was created automatically by mail delivery software. A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: user@ourdomain.invalid SMTP error from remote mail server after RCPT TO:<user@ourdomain.invalid>: host mailbackup.telenet-ops.be [195.130.132.47]: 554 <user@ourdomain.invalid>: Recipient address rejected: Access denied

You need to speak to whoever is providing your backup connection, as they don't recognise your domain or user. Of course expect them to deny their is a problem, as that is what ISPs always do. A common problem is that there is a cluster of servers that answer to the traffic, and one of the cluster members isn't configured correctly. That can often explain why it can work sometimes and others not. Personally I am not a fan of so called "backup" servers because they are usually a spam trap more than anything else. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.