You attach a scanned report, press send, and the email bounces, or never arrives, or your mail app offers to turn the attachment into a link. Email was never designed for large files, and every provider sets a ceiling. Knowing where the ceilings are, and which of three fixes suits your file, gets the document delivered.
The limits that matter
- Gmail lets you attach up to 25 MB in total. Above that it offers to upload the file to Google Drive and send a link instead.
- Outlook.com allows about 20 MB of attachments, and offers OneDrive links for larger files.
- Work and government email servers are often stricter, commonly 10 MB, sometimes less. Your email can leave your Gmail and then be rejected by the recipient's server.
Attachments are also encoded for sending, which makes them roughly a third larger in transit. A file that is just under a limit on your computer can still be over it on the way. Aim well below: under 10 MB is safe almost everywhere, under 5 MB is safe everywhere.
Fix one: make the file smaller
Most oversized PDFs are scans or contain photographs, and they shrink dramatically. Compress PDF reduces the images inside the file; a 30 MB scan commonly ends up at 3 to 5 MB with no visible difference on screen. If colour is not needed, greyscale roughly halves it again.
Before compressing, remove pages the recipient does not need with Delete pages. It is the only way to make a file smaller with no loss of quality at all.
If a typed document is unexpectedly large, the cause is usually something embedded in it, such as a full-resolution photo pasted into a Word file. Fix the source; see why PDF files get so large.
Fix two: split it into parts
When the document cannot be shrunk without becoming unreadable, such as architectural drawings or a long colour report for printing, send it in parts. Split PDF breaks it into ranges; send each part in its own email with a subject like "Report, part 1 of 3". Split at natural breaks, such as chapters or sections, rather than every fixed number of pages, so each part makes sense on its own.
Fix three: send a link instead
Google Drive, OneDrive and Dropbox all let you share a link to a file instead of attaching it. This handles files of any size, but sharing settings deserve thirty seconds of attention:
- "Anyone with the link" means exactly that. If the email is forwarded, the link goes with it. Fine for a brochure, not for a medical report.
- Sharing with specific people means only accounts you name can open it. Use this for anything personal.
- Remove access afterwards. Once the recipient has downloaded the file, stop sharing it, or set an expiry date if your service offers one.
Some offices block file-sharing links for security reasons, in which case compressing or splitting is the only option.
Name it so it gets opened
A large attachment named scan0001.pdf is easy to ignore. Name files for the recipient: Thapa-Ram-loan-application-documents.pdf says what it is and whose it is, and survives being saved into a folder with fifty other applicants' files.