How to Compress Images for Email Attachments and Signatures
Key Takeaways
- Email provider attachment caps (Gmail, Outlook, Yahoo) and why large images bounce.
- Why email signatures must be under 30KB to avoid spam filtering and slow mobile loading.
- How to use Compress to 50KB and Compress to 20KB for reliable portal delivery.
- Balancing pixel dimensions (e.g. 600px width) for desktop and mobile email clients.
Sending emails with uncompressed, high-resolution photo attachments is a frequent cause of delivery failures. Many corporate email servers reject incoming messages exceeding 10MB, and recipients browsing on mobile data will experience frustrating delays.
Here is how to optimize images specifically for email.
Email Attachment Best Practices
- Total Email Budget: Keep total email weight under 5MB to prevent gateway rejections.
- Inline Photos: Compress photos to between 50KB and 200KB before inserting them into message bodies.
- Email Signatures: Logos and headshots inside HTML signatures should strictly be under 20KB to 30KB and under 300px wide.
How to Compress for Email
- For receipts, document scans, or regular photos: Use Compress to 50KB.
- For signature logos or profile icons: Use Compress to 20KB.
- Download the lightweight file and attach with confidence.
Frequently asked questions
What is the maximum recommended size for email attachments?
While providers permit up to 20MB-25MB total email size, individual images should ideally be under 500KB (and under 50KB for signatures and embedded graphics) to ensure instant loading on mobile devices.
Why does my company logo in my email signature appear as an attachment?
Large PNG logos often get flagged as separate attachments. Sizing the logo to 300x100 pixels and compressing it under 20KB prevents this behavior.
Compress email images under 50KB
Private & Client-Side Image Processing
Your images stay safely in your browser. Here is how our architecture protects you:
Image processing is performed locally in your browser memory for all supported tools, so your selected files never need to be uploaded to an external processing server.
No storage or file harvesting. Because operations occur client-side, we never copy, view, or retain your personal photographs or documents.
Instant speed and zero bandwidth costs. With local Canvas and WebAssembly execution, files are processed at full device speed without cloud upload lag.
More guides & articles
How to Compress an Image to 500KB Without Losing Quality
How to Compress an Image to 20KB for Online Forms
