Spam Resource: B2B spam filters and domain blocking: Who blocked my mail?

Al Iverson just published a engaging write-up on Spam Resource:

Let’s compare B2C versus B2B deliverability issues, shall we?In the B2C (business-to-consumer) or DTC (direct-to-consumer) email marketing universe, the number of mailbox providers, while broad, is very heavily concentrated in the US. There are six providers, that when you add up their subscriber reach, they comprise over 90% of almost any typical US B2C email list: Google, Yahoo, Microsoft, Comcast and Apple. Anything beyond the top five is pretty much in the long tail. (That doesn’t mean you ignore deliverability issues for smaller providers, but when you do a cost/benefit analysis of time investment versus reward, it is often clear that fixing an issue with a big provider first will yield more benefit.)In the US B2B (business to business) email universe, things are not as obviously concentrated. There are more providers and it’s not just a set of six controlling just about all of the mailboxes you’ll want to send mail

Read more here: B2B spam filters and domain blocking: Who blocked my mail?