If you are using one of Direct Mail's new, modern templates, you may be curious why the width of the template is set to right around 600px. As we developed these new templates, we were careful to make sure that they looked great in as many email clients as possible—from Apple Mail to Outlook, desktop, web, and mobile. We found that the width that yielded the best results across all email clients is approximately 600px.
If you are using a template that it built with our new editor, it will automatically make sure that your message is fit to this width. It will also make sure that your email resizes appropriately on smaller screens (like mobile devices).
If you find it necessary, for some reason, to create a wider email, we strongly suggest providing your own HTML code, or hiring a professional designer to create a custom template for you. If you do so, please make sure to run a design test so you know what the email will look like in the various email clients your recipients use.
There is a workaround that can force our modern templates to stretch wider, but it is not recommended. If you require this workaround, please contact our support team.