I’ve had people ask me this a bunch of times so I thought I’d write it down.
1) Same as webpages but different… An email template is coded in html same as a webpage. but to do a good job can be way more complicated. With a webpage, for the most part desktop browsers are quite standard insofar as you code a page and it looks pretty similar on all of them. Even responsive websites (ie coded to look different on mobile) oare essentially just coding for different screensizes. There’s a lot less worrying about things looking different on different devices than there used to be.
However, it’s different with emails. Codde it for outlook and it will almost certainly not look the same on gmail. In fact the best way to code emails is with a small subset of very old-fashioned html that is fairly predicatable across email clients. And even that isn’t perfect.
2) Responsive or not? You can have mobile responsive emails. But frankly I wouldn’t bother. For the sake of keeping cost and complexity down I reccomend a fixed width email of about 600px that will look nice on either a phone or a desktop. Focus on making that clearly communicate your brand. That way if there are changes in your brand then you can afford to make those changes because the email code is less expensive to maintain/alter.
3) Placeholders – systems like mailchimp/constant contact/phplist… … heck sometimes we generate the emails within wordpress and paste the code into our email sender…. They all use placeholders. so you have the template with no email content in it. Then someone puts a placeholder in for the date, for the title, for and image, for the content etc. Then mailchimp or whatever creates the actual email out of that.
4) Using built in templates. Be aware… If you use something like mailchimp and use their built in templates the you will be stuck with them and stuck with mailchimp! Although milchimp allows you to custom code your own templates, it does not allow you to alter it’s own templates. So I advise clients not to get pulled in by these attractive starter plans. In years to come they’re stuck with a load of templates that they’ve invested a lot of time and energy creating autoresponders in etc and they’re paying a whacking great monthly bill for their list… I reccomend buying an html template and working with that and ideally hosting your email yourself using PHPlist. That way you can use a service like mailjet for your sending at a fraction of the cost and never get tied into these monthly fees/inflexible mail templates….