Email Attachment Size Limits

You finished the deck, exported the screen recording, and hit send. The message bounces back with “attachment too large.” The limit is not about your file being wrong. It is about how email servers move data.

Why email rejects large attachments

Email was designed for short text, not gigabyte video exports. Every attachment is copied through multiple servers. Providers set hard caps so mail stays fast and storage costs stay predictable.

When your file exceeds the limit, the sending server may reject it immediately or the recipient’s server may strip the attachment. Neither case gives you a useful error on the phone.

Base64 encoding also inflates binary files by roughly 33 percent inside the message. A 20 MB video can behave like 27 MB on the wire.

Some clients show a progress bar that stalls at 99 percent when the server rejects size late in the transfer. Saving a few megabytes below the published cap avoids that frustration.

Typical limits by provider type

Exact numbers change, but these ranges show up often in 2026:

Provider category	Common attachment cap
Consumer webmail (Gmail, Outlook.com, Yahoo)	25 MB per message
Corporate Microsoft 365 / Exchange	10 to 35 MB (admin setting)
Google Workspace	25 MB (larger files via Drive link)
Apple iCloud Mail	20 MB
Mobile carrier email	Often 10 MB or less

Some companies set a lower cap than the provider default. IT may also scan attachments, which adds delay for big files even when they technically fit.

Work accounts sometimes block certain extensions entirely (EXE, ZIP with macros). Video and PDF are usually allowed but still subject to the byte cap. Ask IT for the exact number before you export a client deliverable.

Which file types blow the cap first

Video is the usual culprit. A five-minute 1080p screen recording from a phone or laptop can land at 200 to 600 MB untouched. Even a 30-second clip at 4K can exceed 25 MB. For email-specific export settings, see compress video for email on Mac or how to send large video files on Mac .

PDF decks with full-page photos compress poorly when exported from design tools. A 40-slide presentation with embedded PNG screenshots often sits between 30 and 80 MB. Portal caps often match email limits; see compress PDF for upload limits on Mac .

Images add up fast in batches. Twenty RAW or uncompressed PNG exports from a photo shoot can total hundreds of megabytes. A single TIFF scan may pass alone but fail alongside two more attachments.

Audio is rarely the problem unless you attach uncompressed WAV masters.

Combining file types in one message counts the total. Three 8 MB JPEG files plus a 5 MB PDF can exceed a 25 MB cap even though each item looked fine alone.

How to shrink attachments before sending

Work in this order: trim, resize, then re-encode.

Video: Cut dead air at the start and end. Export at 720p or 1080p instead of 4K. Lower the bitrate or use a modern codec. See the video compression guide for Mac or the Windows video guide for step-by-step exports.

PDF: Re-export with compressed images inside the document. Print to PDF at a lower image quality setting, or run a dedicated PDF pass. The PDF compression guide for Mac covers Preview and other local options.

Images: Resize to the display size recipients actually need. Convert PNG UI shots to JPEG when transparency is not required. Batch-export from your editor at 80 to 85 percent quality. The image compression guide for Mac walks through common formats.

ZIP archives do not help much with already compressed MP4, JPEG, or PDF content. Zipping helps mainly with text, SVG, or uncompressed sources.

If you must stay under an exact megabyte number, measure the exported file in Finder or File Explorer before attaching. A 10 MB cap is common on forms; see how long is a 10 MB video for duration estimates at that size.

Naming helps recipients too. project-review-720p-18mb.mp4 sets expectations better than final FINAL v3.mov.

For mixed folders of screenshots and clips, process video first. It is usually the only file that needs re-encoding. Images may only need a quick resize pass.

When to skip email entirely

Email works for documents under the cap. For anything larger, a shared folder, a ticket attachment field with its own limit, or an internal file drop is often cleaner.

Signs email is the wrong channel:

• The file is still too big after 720p export.
• You are sending the same weekly report to ten people.
• The content is confidential and should not sit on a web upload form.

Keep a compressed copy for email and retain the master elsewhere for editing.

Calendar invites and ticket systems often embed their own smaller limits in the upload widget, separate from your mail provider. Read the error text carefully: “attachment too large” and “upload failed” are not always the same root cause.

Using GetCompress

When you know the limit (for example, 20 MB) but not the exact encoder settings to hit it, GetCompress lets you set target file size on video, use quality presets for images and PDF, preview the result, and export locally without uploading. Drop a MOV, MP4, PDF, or image folder, pick a preset, and save the output beside the original. For recurring sends, save those settings as a preset so the next attachment fits the cap on the first try.