Hello, I use Exchange 2007 and I have some sender (client) that are using for instance wanadoo.fr that is relayed by orange.fr and the email is refused: Objet : Undelivered Mail Returned to Sender This is the mail system at host mwinf2b11.orange.fr. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <Graig@company.com>: host mail.company.com[185.XX.198.225] said: 550 5.7.1 Recipient not authorized, your IP has been found on a block list (in reply to RCPT TO command) My question is: what would be the best solution to bypass those users? I do have the list of the users that should no be block. Shall I whitelist the senders? domain? Would that represent any risk to bypass sender? Would I might receive spam from them is they are on the whiltelist? Shall I whilte list the IP?? See I am a bit confused and would be glad to have some good advice on that. Tahnks to all in advance, Graig

Hi, A better way will be to add the ip to your whitelist. Adding the ip will result in acceptance of mails from that domain but the other content filtering rules will run as it is i.e adding the ip to whitelist only skips the blacklist check and other test will run which will result in less amount of spam to your email server. Thanks.

Thanks for the advice I will then white list the IP :-) Do you know how to get those IPs? Shall I do a nslookup> set type=mx > wanadoo.fr ?? Or there is a better way to obtain the complete IPs used? Maybe I should ask the IT departement.. Graig

Hi, You should know the edge server ip of the sender. You can use the MX records to determine the IP address but if possible you can always ask the admin of the other organization to get it. Moreover logs on your exchange edge transport server can also help you in getting the right IP to whitelist. Thanks.

I did the below command in order to get the IPs used and that the edge has received but I am wondering if: 1) I could check the domain instead --> *wanadoo.fr instead of the client email address? 2) the check will also take on consideration the IPs already blocked? get-messagetrackinglog -Sender "firstname.lastname@wanadoo.fr" -Start "01/09/2010 08:55:00" -End 22/09/2010 09:05:00" | ft ClientIp