Updated Exchange Online Protection Addresses - Jan 2015

Microsoft has indicated that they are going to be updating the Exchange Online Protection addresses in January 2015. Here is a link with the new IP addresses:

• http://technet.microsoft.com/en-us/library/dn163583%28v=exchg.150%29.aspx

What does this mean to you? Well, these are the outbound addresses from EOP to your on premises email system. So, if you are using EOP for your on-premises email system, you need to ensure that your firewall is updated to allow traffic from these IP addresses to your on-premises email system.

Also, it is not explicitly stated, but I would be concerned that mailflow for hybrid environments will be affected. So, it may be necessary to go into the receive connector used for hybrid mailflow and allow these IP addresses there also. I'll try to check on my hybrid system when the changes go into effect in January and update this post.