Developing emails can be as simple as writing some HTML and sending it through an email application, but it’s a bit more nuanced than that when doing complex emails. Here are some tools that help keep me consistent:
Parallels or VMware – I develop on a Mac, so seeing it opened in Windows is really handy for testing emails. Litmus or Email on Acid are great, but having an actual “native” device is great for confirming the render.
Office 365 – Always having the latest Outlook is super important when testing. Of course I keep older versions too, but Office 365 has bailed me out on a number of occassions.
Grunt or Gulp – Build tools are the standard for web development, but tools like Grunt and Gulp are really helpful in email development too for inlining CSS, zipping up folders for uploading to testing platforms, validating HTML, optimizing images, and even sending test emails.
Putsmail – For quick email tests, nothing seems to beat Putsmail (now owned by Litmus). Just paste in your code and send. Just make sure your images are hosted somewhere other than your computer or they won’t show up.
Campaign Monitor – I used to use MailChimp as my testing tool, but Campaign Monitor offers unlimited test sends which is critical for fully flushing out any bugs. I’ve also found that Campaign Monitor’s UI better suits my workflow when developing emails. I wish it had an API I can call directly from my build tools, but that’s getting super geeky.