Came across this thread the other day. Spot on for anyone designing emails, and a great discussion, with lots of amazing shared resources on creating “bulletproof buttons” for email design.
I thought I would take a moment to write up my thoughts, and share some of those resources as well.
Best Resources for Creating Bulletproof Buttons for Email
1) SexyButton – A Responsive, Universal, HTML Email Button
Many of the resources this list includes are home-brewed solutions created by email marketers for their own in-house marketing needs. The “SexyButton” created by BluePrint Interactive is no exception. Not only does BluePrint provide the code for “SexyButton,” they also include a writeup of it’s creation, an explanation of the coding, and examples of how the “SexyButton” renders in different email clients.
Pros: Code available for end user. Button renders correctly. in most common email clients.
Cons: Only code based. Need to know HTML to edit button.
2) Bulletproof email buttons – The Holy Grail of Bulletproof Email Button Creators, Buttons.cm.
Buttons.cm from Campaign Monitor is a very easy tool to choose what options you desire for your button. They’ve included several different examples as well, so you can start from a template and change to what your email design calls for.
Pros: Allows user to change specific parameters of button design. Gives visual example of final button design. Copy HTML code directly from creator.
Cons: If your email template is <table> designed, you’ll need to fix things a bit to make the button work correctly.
3) Cheshire Impact – “Top 5 Free Call to Action Button Generators.”
A great resource from one of the premiere Pardot expert organizations. Cheshire Impact goes through 5 different button generators, each with their own value-adds. Great resource to check out. Be sure to follow them on Twitter as well!
4) Litmus – A Guide to Bulletproof Buttons in Email Design. 
This is more of a background on bulletproof email buttons, which is a good place to start if you’re looking into the reasons why you should include non-image CTA buttons in your email designs. We can still make our designs “pretty” without being reliant on having an image-based email design!