Fix "email attachment too large" errors

The error message changes per provider, but the cause is the same: your email exceeded the per-message size cap. This page explains exactly which limit you hit and the fastest way to send your photos anyway.

Decode the error

Why "under 25 MB" sometimes still bounces

Email attachments are encoded in base64: every 3 bytes of binary become 4 ASCII characters. That's a flat 33 % expansion before MIME headers, which add another few percent. So a 22 MB photo becomes a ~30 MB email after encoding, which exceeds Gmail's 25 MB.

Rule of thumb: divide the advertised limit by 1.37 to get the binary file size you can actually send. Gmail's 25 MB advertised = ~18 MB binary; Outlook's 20 MB = ~14 MB binary.

Method 1: recompress in the browser

The most common case is a few photos slightly over the line. EmailPhotos.com fixes it in seconds:

1. Open emailphotos.com.
2. Drag the bounced attachments onto the page (or pick from your library).
3. The browser compresses each one, balancing quality across the batch so the total fits a 14 MB budget by default: works on every major provider.
4. Press Send. The OS share sheet opens with the bundle attached. Pick Mail or Gmail.

Photos never leave your device: compression runs in Web Workers inside your tab. EXIF and GPS metadata are stripped automatically.

Method 2: share via cloud link

Some emails really shouldn't be re-encoded: wedding archives, RAW files going to a printer, anything large you'll re-export later. Replace the attachment with a link instead.

• Gmail web: Compose → Drive icon (📂) → upload → "Insert as attachment". Above 25 MB Gmail forces "Insert as link" and does the upload for you.
• Apple Mail: attachments over 20 MB trigger Mail Drop automatically: file uploads to iCloud, recipients get a 30-day download link.
• Outlook web: attachments over 33 MB get auto-converted to OneDrive share links.
• WeTransfer: 2 GB free, no signup, link expires in 7 days.

Method 3: split the email

For 30+ photos: send two or three smaller emails instead of fighting one big one. EmailPhotos.com warns when a batch can't fit and suggests how to split. Otherwise: compress, attach the first half, send, then compose a second message with the remainder.

Diagnosing rare cases

"Couldn't send: file is too big": but the file is only 5 MB

Likely cause: you've already added other attachments and didn't realise. Check the compose window for hidden attachments or large inline images. Some clients embed your email signature image or logo as an inline attachment.

Recipient's server rejected the message

Some corporate Exchange servers reject anything over 10 MB. The sender side accepts; the receiver side bounces. There's no way around this except shrinking the attachment or using a share link.

"Antivirus removed an attachment"

Not a size error: but worth knowing about. Some corporate filters strip HEIC, .heic, or executable file extensions. Convert HEIC to JPEG (EmailPhotos.com does this automatically) or use a different delivery method.

What size to aim for

• 14 MB binary if you don't know the recipient's provider: works everywhere.
• 22 MB binary if you know they use Gmail, Yahoo, or Proton: leaves headroom under 25 MB.
• 45 MB if you know they use Fastmail or a corporate Microsoft 365 with the default cap.

EmailPhotos.com's default budget is 14 MB for exactly this reason.