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How To Send Big Files Over Email

First, you need to know why you shouldn't attach big files.

Sending files by email isn't space efficient. Internally, the computer needs to re-enode the contents of the file(s) for transmission that will work, even if your email passes over a historically old system. This results in nearly doubling of the size of the file! It also makes delivery slow.

That double-sized content then sits in your outbox, and if you cc'd yourself then also your inbox, it takes twice as long to send going through the network, has to go through a slow virus checking process, and then copies also sit in each recipient's inbox (or later archive folders or trash), and a cached copy likely eats up their computer's disk space too. You're not doing anyone any favors.

This extra space can also eat up storage quotas, resulting in mailboxes that become full and no one then can deliver content to them (until they go on a deleting spree).

Mail systems also impose limitations on the size of the content it will transmit. They're not all the same; what may work for one email address may not work for another.

The Reliable Way

The more reliable way to send one or more big files is to compress them first, then upload the files to a service that will temporarily hold them for you. A link to the content is provided in an email, and once the recipient has acknowledged receipt, remove them. Some services will automatically take care of this process for you.

Apple Mail

If you happen to be using Apple Mail, then Apple can take care of this for you automatically! Using a free service called Mail Drop, you can send files as large as 5 Gigabytes each, they are available for pickup for 30 days, and you can have 1 Terabyte pending at any given time.

Turning on MailDrop: Go to Mail / Preferences..., click on the Accounts tab, select your account from the list on the left, and in the Account Information sub-tab, be sure that "Send large attachments with Mail Drop" is checked. That's it!

File Transfer Services


TransferNow allows you to send file up to 4 Gigabytes as guest, 20 Gigabytes if you register. You can password protect the files and even expire them early. You also get an email notification when someone receives the files. The interface is as easy as drag'n'drop, no software install is required, and you do it right from the browser. They even have videos of how to send files and generate shared links.


WeTransfer presents a little email form on the screen, where you put you to address, your from address, a short message, and add your files. Registered accounts can adjust expiration times and password protect the content.

Compression Utilities

While more of an advanced topic, you can take one or more files, independently compress and password protect them, generating an archive that you can then forward.

Here are the more popular tools:

  • 7zip — free: super high compression (makes 7z, XZ, BZIP2, GZIP, TAR, ZIP and WIM files)
  • WinZip — windows-only, paid-only: standard compression (makes ZIP files)