Why email rejects large images
Mail servers limit attachment size to protect storage and delivery speed. A single modern phone photo can exceed an entire message quota. Multiple photos multiply the problem quickly.
Mobile data matters too. Recipients on slow connections may not wait for a 15MB download. Smaller attachments arrive faster and feel more considerate.
Some companies strip large attachments entirely, replacing them with a notice that the file was removed. Compressing before sending avoids that silent failure.
- Gmail: roughly 25MB total message size
- Outlook and Exchange: often 10–20MB limits
- Corporate gateways: sometimes under 5MB
- Mobile recipients: slow on large files
Resize before you compress
Email viewers rarely show images wider than 800–1200 pixels. Sending a 4000-pixel original wastes space without improving what the recipient sees.
Resize to the display size you expect — full width for a newsletter inline image might be 600 pixels; a photo a colleague will open separately might be 1600 pixels max.
After resizing, compression has less work to do and quality stays higher at the same file size.
Best format and quality for email
JPG is the safest choice for photos in email because every client displays it. WebP is smaller but some desktop clients still render it inconsistently in 2026.
Use PNG only for screenshots with text or logos needing transparency. PNG photos are unnecessarily large.
Quality between 70% and 80% is the sweet spot for email photos. Check one image at full size before batch-processing the rest.
Step-by-step compression workflow
Select all images you plan to attach. Open the Irreva Image Compressor, drag them in, and set quality to around 75%.
Review total size in your file manager after download. Aim for well under your server's limit — under 5MB total per message is a safe target for corporate recipients.
Attach the compressed files, add a short note describing the content, and send. If files are still large, resize further or split across two messages.
Compress email attachments on Irreva
The Irreva Image Compressor shrinks photos in your browser before you attach them. No upload to a third-party server, no watermarks, no account required.
Batch-process a whole set, download a zip, and attach the smaller files. Your message sends on the first try, and recipients get images that open quickly on any device.