Why one client freezes and the rest don't
Classic desktop Outlook, roughly the 2007 through 2019 releases, doesn't render email with a browser engine. It uses Microsoft Word's, and Word treats an animated GIF as a photograph: frame one, rendered once, forever. The modern family (new Outlook for Windows, Outlook.com, Outlook mobile) animates normally as of mid-2026.
You can't detect which build a recipient runs before sending, and the classic versions cluster exactly where you'd least want them, on locked-down corporate machines that IT upgrades on a geological schedule. Fighting this is pointless. Designing around it is cheap, and the design move fits in one sentence: choose a first frame that needs no animation. The classic share shrinks every year as companies migrate, but any list with corporate domains still carries enough of it to matter.
Pick the frozen frame on purpose
Left to chance, a GIF opens on garbage: a cursor mid-flight, an interface half-drawn, a face between expressions. Harmless when everything animates, fatal when that frame is the whole show. In What the GIF, cuts snap to individual frames, and each press of an arrow key crawls the start point by exactly one, so you can audition opening frames until you find one you'd ship as a screenshot.
If the strongest image sits at the end of your clip, reorder reality. The tool chains as many as 10 clips together, so the payoff can open the loop and the process can follow. By default the first clip sets the output frame, later clips are fitted to it, and the joins are hard cuts, which is what email wants anyway. Nobody on the receiving end knows the order changed; they just see the good part first.
A caption with no timing is frame-one insurance
Text baked into the pixels survives anything a rendering engine does, short of blocking the image outright. You get up to 3 overlays per GIF: a clean typeface with a color picker, or the classic white-with-black-outline meme look. Anchor them top or bottom, or drop them freehand anywhere in the frame. Meme lettering shouts in a work inbox, so most senders reach for the clean style and save the shouting for social.
The Outlook-specific rule: leave the first caption's timing fields empty. Untimed captions render across the entire GIF, which puts them on frame one by definition. A caption timed to enter at second two simply never happens for a frozen-frame reader, so save timed reveals for the second and third overlays and let the headline hold the whole loop.
The rest of the inbox still grades on weight
The freeze is Outlook's quirk; everything else is shared inbox economics, all figures approximate because platforms nudge them:
- About 1MB of file, ideally less. Heavy messages drag on deliverability before they drag on anyone's patience.
- Roughly 600 to 640px wide, the standard single-column layout. Wider exports buy nothing visible.
- 10 to 15 fps. Inbox motion doesn't need more, and frames are the currency the file is priced in.
- 64 to 128 colors. Product shots and UI recordings shrug off palette cuts; the projected output size shows each saving as you commit it.
- Alt text, always, for the clients that hold images hostage until the reader opts in.
Gmail deserves one cross-reference: it animates fine but clips message HTML past roughly 102KB and proxies every image through Google. Details in the Gmail guide; the general sizing doctrine lives in GIFs in email.
Converted where the footage already lives
The whole build happens inside one browser tab: drop in an mp4, mov, webm, avi, whatever decodes locally, then trim, caption, crop to a locked ratio (1:1 or 16:9 both suit an email column), shrink the dimensions, cut the colors, export. No signup gate, no watermark on the result.
Nothing you load is transmitted anywhere, which matters plenty when the footage shows an unshipped feature, or a customer's data lurking in the corner of a screen recording. If the export still overshoots the budget, the small-GIF recipe squeezes further.