Why is the Preview & Schedule button greyed out?

This guide covers every reason the Preview and schedule button can be disabled, in order of how often you’ll see them, and how to fix each one.

Start here: hover the button for a tooltip

Before hunting through fields, hover over the greyed-out button — Letterhead shows a tooltip explaining why it’s disabled. Two messages cover most cases:

• “Please fill out the required fields to save and schedule.” — a required field is missing or invalid. Most common cause; see Cause 1.
• “You can’t schedule this while your email provider is disconnected. A company admin can reconnect it in Settings > Integrations.” — the sending integration on your channel has a credentials problem. Not fixable from the letter; see Cause 5.

An auto-save never greys the button: the status beside your avatar reads Saving… while one runs, but you can click Preview and schedule regardless, and the composer finishes the save before it builds your preview. If the tooltip says nothing and the button is grey, something other than an auto-save is still working — the preview build itself, an import, or a settings change being written — and it comes back when that finishes. While the preview is being built, the button names the step it’s on — Saving…, Rendering…, Opening… — and the status beside your avatar says the same in full, so you can tell a build in progress from a button that’s stuck.

Cause 1: A required field is missing

On the Preview and schedule step, the right-hand sidebar marks required fields with a red asterisk:

• Email Subject
• Preview Text (also acts as the letter’s subtitle)
• Audience
• Date and Time

If any is blank, the button stays disabled. Filled them all and it’s still grey? Click out of each field once more — Letterhead validates when you leave a field, so a field can look filled but not be registered. Re-hover the button; if the tooltip is gone, you’re good.

Cause 2: Social card text is too long

Custom Social Card fields each have their own character limit, and going over shows a validation error: Title is limited to 80 characters, Preview text to 180. Trim the field — titles are best around 60–70 characters anyway (social platforms truncate), and preview text around 150.

Cause 3: An HTML block has invalid HTML

If an HTML block in your letter body can’t be parsed, scheduling is blocked. Go back to the compose step and look for an HTML block with an error indicator; fix the markup (unclosed tags, missing quotes) or delete the block. See How can I use HTML in Letterhead?

Cause 4: A UTM tracking parameter is invalid

A malformed UTM parameter on your channel’s links blocks scheduling — typically a missing =, an invalid character, or an empty key. Look for an error indicator next to your link settings, or ask whoever manages the channel’s link settings. See Tracking & UTM codes in Letterhead.

Cause 5: The channel’s ESP integration is broken

If your channel’s email service provider is disconnected, the tooltip reads: “You can’t schedule this while your email provider is disconnected. A company admin can reconnect it in Settings > Integrations.” This can’t be fixed from the editor — an admin needs to reconnect it in Settings → Integrations.

Cause 6: A/B test isn’t fully set up

If you enabled an A/B test but the second subject line (or another A/B field) is blank, the button stays disabled. Complete the setup or turn the test off.

Cause 7: Something other than an auto-save is still working

An auto-save doesn’t disable the button — you can click Preview and schedule while one runs, and the composer finishes the save before it builds your preview. The button does go grey while the composer is doing something it has to finish first: building the preview after you click (it walks through Saving…, Rendering… and Opening…, and the status beside your avatar names the same steps in full), importing a document, or writing a tracking setting. If it doesn’t return to Preview and schedule, or move on to the next step, within ~10 seconds, refresh the page (your changes are autosaved) and try again.

Still stuck?

1. Refresh the page — your work is autosaved.
2. Check the browser console for errors (Cmd+Opt+J on Mac, F12 on Windows); screenshot any red error.
3. Contact support with the letter’s Unique ID, the channel, and a screenshot of the scheduling sidebar.