Hi,
I'm in the process of configuring one of our clients Office 365 setup so that they can utilise Exchange Online Protection. The client has an Exchange 2013 setup on premise and I would like to use their configured Exchange Online Protection service to route mail through as a smart host, once I've got outbound mail configured I'll look at routing the inbound mail through, it's all configured just need to update the clients MX record so they will be utilising EOP.
The client is currently routing mail via our hosted Exchange environment. The reason being they are routing mail through our hosted Exchange environment rather than direct from site is down to their WAN connection. Unfortunately they share a 100mb pipe with about 30 other businesses via the local council, as they share this WAN connection with other businesses all going out on a proxy server this has caused no end of problems with the main problem being their public IP address is consistently on a blacklist. Routing mail from their on premise Exchange server out through ourselves as a smart host has resolved the issue.
When I route mail from their on premise Exchange server over to their configured EOP connector then any sent mail from site bounces back with the following NDR:
alex.derbyshire@domain.com
DB3FFO11FD058.mail.protection.outlook.com
Remote Server returned '550 5.7.1 Service unavailable; Client host [*.*.*.*] blocked using Spamhaus; To request removal from this list seehttp://www.spamhaus.org/lookup.lasso'
So it would seem that when using an EOP as a smart host doesn't help when the sending mail server's IP address is on a blacklist. I have always been under the impression that using a smart host counteracts this problem? Would I be right in saying as their domain is configured in EOP and their public IP is on the inbound connector in EOP then there shouldn't be any policies checking the outbound mail ?
It would be great to have this setup as having them using our businesses hosted Exchange environment isn't ideal.
Looking forward to any ideas!
Alex
