Deliverability, Return Path, List-Unsubscribe Header

Here are a few blog posts covering the email industry from Constant Contact, Return Path, and SpamResource.
Constant Contact posted a blog post about how they measure email deliverability on January 10^th.  They started with just tracking bounce backs and using that metric to calculate deliverability but then moved to using seed list through a third-party and report that they get 97% deliverability.  Read more at Constant Contact
On January 6^th, Return Path recapped their most read blog posts which includes covering Yahoo’s DMARC Reject Policy, Blacklist Basics, and GMails new FBL and Unsubscribe button. Read more at Return Path
Return Path and SpamResource both have an excellent write-ups about the preference change at Outlook.com/Hotmail regarding the List-Unsubscribe header.  Microsoft, like Google, prefers to use mailto instead of http or other URI protocols for the List-Unsubscribe header.