File Size Deliverability

Jake, there are a couple of problems that could be affecting your open rate now.

Email file size definitely affects deliverability. Once you cross the 110k file size, there are several email clients that immediately dismiss your email as spam. This includes Apple Mail, certain versions of Outlook, Google Apps and Yahoo. (Source)

Email file size also effects open rates and engagement. Large, bloated code in an email takes a long time to load and render. According to Litmus, “51% of recipients delete your email within two seconds of opening it.” Your recipients are likely insta-deleting your emails because it is taking much longer to load.

So I have two questions for you:

1. Why did adding responsiveness triple your email file size? When we took our largest, longest email and made it responsive, it increased the size of our email by only 33%-50%. You might want to consider Litmus Scoping your email so the friendly neighborhood community could take a look and see if your code could be optimized.

2. Are you minifiying your email before you send? Although indentation and line breaks make it significantly easier to create and maintain your emails, all that whitespace is poisoning your open rates. For example, removing indentation and unnecessary whitespace cut a recent email from 108k to 83k - that's 30% smaller free-of-charge. I recently published a blog article talking about the advantages of minifying your email before you send.

Good luck!

Hey Jake - while your email is by no means small, 115KB shouldn't be affecting deliverability alone. Is it possible there are issues or irregularities in your code that could be triggering spam filters?

Here's a helpful write-up from ET that I'll sometime reference regarding email file size: http://www.exacttarget.com/blog/email-file-size-guidelines-time-for-your-checkup-part-1-of-3/