Free tool
See your email in real inboxes.
Paste your email’s HTML and we’ll send it to our own Gmail and Outlook.com test inboxes, then photograph it there, on a desktop screen and at phone width (the web inbox in a narrow window, not the phone apps). You’ll also see whether Gmail clipped it in our test inbox.
In Letterhead, the weight check runs while you write.
The composer weighs every issue and shows what’s making it heavy, so you can trim before Gmail clips it.
The Letterhead Brief
You’re on the list.
The Brief lands once a week. Want these checks running on your own newsletter? Book a test drive →