Email is still the default way to send a file — until the file is a few megabytes too big. This page lists the current email attachment size limits of the main providers, explains why an attachment under the limit can still bounce, and compares the workarounds when a file is too big for email.
What are the attachment size limits of each email provider?
Limits for personal accounts as of 5 November 2026, from each provider's own help pages.
| Provider | Attachment limit per message | Built-in way for bigger files | Notes |
|---|---|---|---|
| Gmail | 25 MB | Google Drive link, inserted automatically | Workspace limits set by the admin |
| Outlook.com | 20 MB or 25 MB (Microsoft pages differ) | OneDrive file as link, up to 2 GB | Free Microsoft accounts have 5 GB of OneDrive storage |
| Outlook with Microsoft 365 (work/school) | Set by your organisation | OneDrive / SharePoint link | Ask your IT admin |
| iCloud Mail | 20 MB | Mail Drop, up to 5 GB, 30-day links | Mail Drop has its own 1 TB storage limit |
| Yahoo Mail | 25 MB total | Share a cloud link | Applies to incoming and outgoing mail |
| Proton Mail | 25 MB (outgoing) | Proton Drive link | Same on free and paid plans |
Two practical rules follow from this table: anything above 20 MB is risky to attach no matter which provider you use, and every provider's answer for bigger files is the same — send a link.
Why does an attachment under the limit still fail?
Three reasons, in order of how often they bite:
- Encoding overhead. Email was designed for text, so attachments are converted to text (Base64) for transport. That makes them roughly a third larger: an 18–19 MB file can already fill a 25 MB message.
- The recipient's limit. Your provider may accept 25 MB, but the recipient's company server may stop at 10 MB. The message bounces on their side.
- The whole message counts. Limits apply to the total of all attachments plus the body — three 9 MB files in one email are 27 MB.
Is the limit per file or per email?
Per email. Gmail and Yahoo state the limit as the total of all attachments in one message. You can send several emails with a few files each, but for more than a handful of files that gets messy fast — the recipient has to collect and reassemble everything.
What are the workarounds when a file is too big for email?
| Workaround | Size it handles | Effort for you | Effort for the recipient | Stored on a server? |
|---|---|---|---|---|
| Compress the file (PDF, images) | Gets a few MB under the limit | Low | None | In mailboxes |
| ZIP the files | Small gain; almost none for photos and video | Low | Extract the ZIP | In mailboxes |
| Split across several emails | Tens of MB | High | Collect all parts | In mailboxes |
| Cloud drive link (Drive, OneDrive, Dropbox) | Your storage quota | Upload first | Click a link | Yes, until deleted |
| iCloud Mail Drop | 5 GB | Upload first | Click a link (30 days) | Yes, 30 days |
| Transfer service (WeTransfer free) | 3 GB per transfer | Upload first | Click a link (3 days) | Yes, 3 days |
| StrongFolder link | No limit set by the service | None — no upload | Click a link | No |
Shrink the file
For a PDF that is just over the limit, shrinking is the quickest fix: Acrobat's Reduce File Size, the Reduce File Size filter in macOS Preview, or Compress Pictures in Office before exporting. Details in how to send large documents.
Use your provider's built-in link
Gmail does this automatically with Google Drive, Outlook.com with OneDrive, and iCloud Mail with Mail Drop. It is the path of least resistance, but the file uses your cloud storage and a copy stays on the provider's servers.
Paste a direct transfer link into the email
With StrongFolder you don't attach or upload anything. Choose the file or folder, copy the link and paste it into your email. When the recipient clicks it, their browser downloads straight from yours over an encrypted connection. Files are never uploaded to or stored on a StrongFolder server. No size limit set by StrongFolder. The practical limits are free disk space on the recipient's device, connection speed, and how long both devices stay online.
The one condition: The sender's browser tab must stay open and online until the recipient finishes downloading — files come from the sender's device, not from a server. If you send the email at night and the recipient reads it in the morning, use a cloud link instead.
Free · in your browser · no sign-up
Can I increase my email attachment size limit?
Not on a personal account — the limits are fixed by the provider. On business accounts (Google Workspace, Microsoft 365) administrators can raise or lower the limits within what the provider allows. Even then, the message must also fit the recipient's server, which you don't control. That is why sending a link is the reliable answer for anything large.
When should I still attach the file?
Attach it when it is comfortably small (a few MB), when the recipient needs the file inside the email thread for records, or when their organisation blocks cloud links. For anything else — videos, photo sets, large PDFs, whole folders — a link is faster and more reliable. See how to send large files for every method by size, and how to send large video files for footage.
Summary
Email attachment size limits sit between 20 and 25 MB for every major provider, and encoding eats about a third of that. For bigger files, send a link in the email: your provider's cloud link if you can't stay online, or a direct StrongFolder link if you want no upload, no size cap from the service and no copy left on a server.