When your attachment is too large to email

I write these guides from the experience of preparing real filings, not as a lawyer or an immigration adviser. Every figure I quote links to its official source with the date I checked it. If something here is out of date, write to me and I will fix it.

It bounces, or the recipient never gets it, or worse, they think they did. There is almost always a better answer than uploading it to the cloud and sending a link.

The real limit is lower than the advertised one

Mail providers publish a maximum attachment size, and that number misleads you twice.

First, technically. Attachments are re-encoded for transport, which inflates them by roughly a third. A 20 MB file travels as about 27 MB. If the limit is 25 MB it fails, even though the file on your disk is smaller than the limit.

Second, there are two limits, not one: yours and the recipient's. Your provider may accept 25 MB while their corporate server cuts off at 10. The message leaves, then bounces hours later, or vanishes silently.

So the practically safe figure is well under the advertised one. Around 10 MB gets through almost anywhere. Above that you are betting on the other side's configuration.

Why a cloud link is usually the wrong move

The instinct is to upload it and send a link. That works between friends and fails in formal contexts, for specific reasons:

• Corporate filters block links to file-sharing services, especially from outside the organisation
• The recipient often needs an account, or has to request access, which costs a day
• Links expire, and the file disappears exactly when someone goes looking for it weeks later
• In a legal filing, a tender or an application, a link is not part of the record. An attachment is

When the send has formal weight, the file belongs inside the email.

Shrink the send, not the quality

Nearly all the weight in an email full of documents comes from scans and photos. A contract exported from Word weighs a few hundred kilobytes. A single phone photo of a passport can be five megabytes on its own.

The right way to reduce it is to treat the send as a set: pick a limit, in this case the mail limit, and size every attachment against that total. Compressing one at a time in the dark is how you end up over-compressing the last one and ruining it.

Set 10 MB as the limit and watch the running total. Text pages are left untouched, so a contract stays crisp, and only the scans get adjusted, which is where the weight actually is.

One attachment or several

If they are related documents somebody will read straight through, merge them into one PDF. One tidy attachment beats eight, and it removes the risk of forgetting one.

If they are independent, send them separately with clear names, so the recipient can forward just the one they need without dragging the rest along.

Zipping almost never helps

It is most people's first idea and it is usually useless. A PDF containing scans is already compressed internally, so wrapping it in a ZIP saves very little, sometimes nothing.

And it adds two problems: many corporate filters block ZIP files outright as a security measure, and the recipient has to unzip it, which on a phone is genuinely annoying. Actually reducing the PDF beats wrapping it.

Name the files as if someone will search for them

Because they will. scan_001.pdf tells nobody anything. 01_passport_maria_gomez.pdf does. If you are sending several separately, numbering them in order means they sort correctly in any system.

Before you hit send

• Check the combined weight of all attachments, not each one
• Stay under 10 MB if you do not know the recipient's limit
• Open each compressed attachment and confirm seals and signatures are readable
• For anything formal, attach rather than link

Common questions

What is the real maximum size for an email attachment?

It depends on both the sender's and the recipient's provider. Around 10 MB passes almost anywhere; above that you depend on the recipient's server configuration.

Why does my 20 MB file fail a 25 MB limit?

Attachments are re-encoded for transport and grow by roughly a third, so a 20 MB file travels as about 27 MB.

Does zipping reduce the size of a PDF?

Barely. A PDF containing scans is already compressed internally, and many corporate filters block ZIP files.

Is it better to send a cloud link instead?

For informal sends, fine. For applications, tenders or anything with formal weight, the file should be attached so it forms part of the record.