Since we posted this blog post, we have received positive responses from many of our customers, who have proceeded with changing their connectors (as per instructions in the post), thereby protecting their email/domain reputation. However, we are also aware of customers who are either in the midst of making this change or need some additional time to complete their changes. We understand a change like this can take some time, so we have decided to move our deadline from Feb 1st, 2017 to July 5th, 2017.
We have also added more details in the original post. If you are an Office 365 email customer and your organization is hybrid (you have an on-premise environment), please take some time to read it!