Yep - you heard right. Back in 2005, George Bilbrey of Return Path wrote a blog "It's not your ESP - it's YOU!" and MarketingProf's also published an article recently "Email Deliverability is in Your Hands". This seemed to be the theme which was threaded through many of the presentations at both the London DMA's recent conferences. It appears that most marketers seem to think that they can buy deliverability - by changing ESP's or paying for accreditation. However, neither of these solutions will work unless the marketer is doing Best Practise.
From a combination of attending these conferences and with conversations with Dennis Dayman, Stephanie Miller and David Daniels, combined with my own experiences - I have come to the conclusion that deliverability is a 2 part process, both of which require due attention and ownership by the marketer:
Part 1 - Deliverability to ISP's - IP Reputation: This is a combined effort by the ESP and the marketer. The ESP needs to have everything ready and waiting for the Best Practise Marketer. Things such as the infrastructure, whitelisting, delivery monitoring, Feedback Loops, education about Authentication and enabling/assisting clients to become authenticated are all things which the ESP can do.
However, the main causes of emails not being accepted by the ISP is due to the percentage of spam complaints and bad addresses....and having a clean and up to date database is the responsibility of the marketer. This is where having a good Sender reputation is crucial and if you're on a dedicated IP address - well, hey..there's no one to blame but yourself if your reputation isn't as good as it could be.
Part 2: Deliverability to the Inbox - Brand Reputation. So, you got accepted by the ISP/mail server and they have delivered you to the recipients email client? Excellent - but will it be delivered to the inbox or the junkmail folder? This is where your brand, sender name, subject line, good clean coding, choice of copy, domain reputation, message relevance and things like image to copy ratio are taken into account - both by the spam filter and by the recipient.
ESP's can assist you with all of the above factors - but ultimately, the responsiblility of deliverability comes down to you, the marketer. Therefore, if your deliverability isn't as good as it should be - look to implementing Best Practices rather than changing ESP's.