What matters for email images?
Two things decide whether an email image works: size and compatibility. The file has to be small so the message sends quickly, slips under attachment limits, and loads fast on phones and slow connections. And it has to be in a format every mail client can display — Gmail, Outlook, Apple Mail, Yahoo, and the dozens of apps your recipients actually use. A beautiful image is worthless if it never sends or shows up as a broken box.
That narrows the safe choices to two old, universally supported formats: JPG and PNG. Here's how they compare with the newer formats people sometimes try to send.
| Format | Compatible in email? | Best for |
|---|---|---|
| JPG | Yes — everywhere | Photos and detailed images |
| PNG | Yes — everywhere | Logos, screenshots, sharp edges, transparency |
| WebP | Patchy — some clients fail | Websites, not email |
| AVIF | Poor — widely unsupported | Modern websites, not email |
| HEIC | No — often won't display | iPhone storage only — convert first |
Why is JPG best for photos in email?
For photographs — anything with soft gradients, skin tones, or scenery — JPG is the right choice. It compresses photos to a small fraction of their original size while still looking great on screen, so the message sends quickly and loads instantly. Just as important, JPG has been supported by every email client and device for decades, so there is essentially zero risk the recipient can't see it.
If your photo started as a PNG or a phone snapshot, you can convert PNG to JPG to get a much smaller, email-friendly file before you attach it.
When should you use PNG in email?
PNG is best for logos, screenshots, charts, and any graphic with sharp edges, text, or flat areas of color. It keeps lines crisp instead of smudging them the way JPG can, and it supports transparency — which is exactly what you want for a logo in an email signature that needs to sit cleanly on any background color.
Like JPG, PNG displays reliably in every mail client, so a transparent logo or a clear screenshot will look the same for every recipient. The one trade-off is file size: detailed PNGs can get heavy, so it's worth running them through a PNG compressor before sending.
Why avoid WebP, AVIF, and HEIC in email?
Newer formats save space, but email is the wrong place for them. Many mail clients and recipients still can't render WebP or AVIF, so the image may show up as a broken icon or nothing at all. They're great on websites, where the browser handles the format — but you can't control which app or device opens your email.
HEIC is the biggest trap. iPhones often save photos in HEIC, and if you attach one straight from your phone, plenty of recipients simply won't be able to open it. The photo that looked perfect on your screen never appears on theirs. The fix is simple: convert the HEIC photo to JPG before sending so it works for everyone.
How do you keep email images small?
Even with the right format, big files cause problems — slow sends, bounced messages over attachment limits, and sluggish loading on mobile. Resize the image to the width you actually need (a photo doesn't need to be 6000 pixels wide for an email) and compress it before sending. A little compression on a JPG or PNG is invisible on screen but can cut the file size dramatically.
For step-by-step tips on trimming graphics down, see how to reduce PNG file size, and if you're still deciding between formats, the PNG vs JPG comparison breaks down which to pick.
Frequently asked questions
- What is the best image format for email?
- Use JPG for photos and PNG for logos, screenshots, and graphics with sharp edges or transparency. Both are small and display in every mail client, so your image always shows up.
- Why won't my iPhone photo show up in email?
- iPhones often save photos as HEIC, which many mail clients and recipients can't display. Convert the photo to JPG before sending so everyone can see it.
- Can I use WebP or AVIF in email?
- It's risky. Several mail clients still don't render WebP or AVIF, so the image may appear broken or blank. Stick to JPG and PNG for reliable delivery.
- How small should email images be?
- Keep them modest — resize to the width you actually need and compress before sending. Smaller files send faster, dodge attachment limits, and load quickly on slow connections and phones.