It's absolutely possible to use your custom design in MailChimp. However, in order to use your design as a template it will need to be uploaded as an HTML file. MailChimp is designed to send emails coded in HTML, so unfortunately creating a template by simply uploading a PDF, Word, Publisher, Photoshop, or image file wouldn't be a possiblity.
If you'd like to use the design you've already created as a template, the file has to be converted to HTML and then manually coded for email. In order to convert your PDF to an HTML email, you need to be knowledgable and familiar with how to code HTML.
Once the file has been coded you can add our MailChimp template language to create editable regions in your design. The HTML file can then be imported to the My Templates section of your account and used to send campaigns or autoresponders to your list of subscribers. The steps in this article walk you through the import process.
If you don't want to convert your file or don't know how to use HTML, this article gives you several alternatives to create a campaign. If you'd like to use one of our templates you can upload your PDF file to our servers. We'll host the file for you and add a link to the file right in your newsletter.
This feature is available to users with Author level or higher permissions. Take a look at this article to learn more about the different access levels for a MailChimp account.
Spam filters like to see a good balance of text and image content in HTML emails. If you send a campaign that contains image only content, it will have a really hard time getting past most spam filters. We suggest that you add a paragraph or two of text to your HTML version of your campaign (outside of the image, text embedded on an image won't count) to help lower your spam filter score.
Since you're providing your own HTML, don't forget that you'll need to host your images on your server (no free servers - there will be bandwidth issues). And make sure you're coding all links as absolute links that point directly to your server.