We just launched a new feature in MailChimp, where we automatically generate a mobile friendly version of your email campaign, and send it to your mobile subscribers.

For example, if your HTML email looks like this:

and one of the subscribers on your list had the “mobile” preference selected when they signed up for your list:

the email they receive would be automatically formatted for their mobile device, like this:

Generally, images are smaller, and content is stacked into a single column.

If you’d like this enabled for your MailChimp campaigns, make sure that your signup forms have this option checked under your list “defaults” setting:

If your signup forms already had this option on, then the feature is retroactively automatic. If you’re using your own code for your signup form (advanced mode) then you’ll need to add a “mobile” option to your code for this to work.

And speaking of mobile email marketing:

• Check how your email campaigns render on some mobile devices with our Inbox Inspector
• MailChimp campaign archives auto-detect mobile browsers
• MailChimp for iPhone
• MailChimp for Android
• MailChimp Yahoo Mobile Widget
• Pre-headers and mobile devices
• Mobile Email Design Tip: The 250px Magic Box