The email composer uses Unlayer in email display mode. Unlayer's toolbar includes a mobile preview toggle that switches the canvas between desktop and mobile views. Use it to check how your layout reflows before saving.

Multi-column row blocks can render poorly on narrow screens. Use single-column structures for the body of your message. If you need side-by-side content, test it in the mobile preview before saving.

Unlayer lets you set image width as a percentage or a fixed pixel value inside each image block's settings panel. Setting width to 100% lets the image scale down on smaller screens. Fixed pixel widths above roughly 600px will overflow on most phones.

Small text does not scale up automatically on all email clients. Set body text to at least 14px and headings to at least 18px inside the text block settings in the composer.

The campaign page has a "Send Test Email" button. Clicking it saves your draft and sends a copy to your account email address. Open it on a phone to confirm rendering before you send to your list.

The "Preview Text" field on the campaign settings screen controls the short snippet that appears below the subject line in most mobile mail clients. Fill it in. Leaving it blank lets the mail client show the first line of your email body instead, which is often technical content like an unsubscribe link.

The "Design" / "Plain Text" toggle above the composer switches between the visual design editor and a plain text editor. In plain text mode, the email sends without the Unlayer HTML layout, so images, buttons, and column structures are removed.