Behold the Power of Mail Drop

I find myself emailing files all the time to clients, family members and vendors. In most cases, these files are fairly small, so it's not a big deal to email them. Occasionally, however, I will run into a situation where I need to send a large file. This file could be a series of images, a video... anything. The problem with doing this is that Email is extremely inefficient, and most mail providers set a limit on the size of messages (in some cases, as little as 10 MB).

In situations like this, you could use a cloud-based storage system like Dropbox or iCloud Drive to upload the file to, then send a link to the recipient, but that requires a few extra steps, and it can make it a little more inconvenient or confusing for the recipient. Mail Drop to the rescue!

Using Mail Drop seriously couldn't be easier because it's 100% automatic. In fact, I would bet that many of you have used it without even realizing it. There are two requirements to using Mail Drop:


  • OS X Yosemite v10.10.3 or later
  • iTunes 12 or later
  • Safari 8 or later, Firefox 22 or later, or Google Chrome 28 or later
  • iWork for Mac (Pages 5.5 or later, Numbers 3.5 or later, Keynote 6.5 or later)


  • Microsoft Windows 7 or later
  • iCloud for Windows 4.1 or later
  • iTunes 12 or later
  • Outlook 2007 or later
  • Internet Explorer 10 or later, Firefox 22 or later, or Google Chrome 28 or later (desktop mode only)

When you're ready to send a large file, simply compose the new message like you normally would in Mail, including the attachment(s). If the total message size is less than 20 MB (the default minimum file size for Mail Drop), your email will be sent as normal, with the attachment(s) being embedded in the message. If the total message size is larger than 20 MB, the attachment(s) will be automatically uploaded to iCloud storage, and a link will be provided to the recipient. When the recipient taps or clicks on the link, the file is downloaded to their device locally. This link is active for 30 days. The maximum file size is 5 GB (yes, GIGA-bytes). This works for Mac, PC and iOS devices.

In some cases, 20 MB might exceed the recipient's mail server limitation. While there is no obvious way to change that default minimum size in the OS X or Mail interface, there is a terminal command that can be run to adjust the size. This is also useful if you just want to force Mail Drop functionality for every attachment sent, or even none of them (effectively disabling Mail Drop).

The change the default minimum size from 20 MB to something larger or smaller, we'll need to open Terminal (Applications > Utilities > terminal). With Terminal open, type the following command:

defaults write minSizeKB 10000 <enter>

This will adjust the minimum Mail Drop size to 10 MB (the size is in KB). To raise the limit to 30 MB, you would use the following command:

defaults write minSizeKB 30000 <enter>

You get the idea. If you want to revert back to the default 20 MB setting, simply use the value "20000" in place of a custom value.

If you want to effectively disable Mail Drop, use the following command:

defaults write minSizeKB 5000000 <enter>

This will set the minimum size equal to the maximum size, canceling each other out. While this is technically possible, I strongly recommend not doing this. Why would you not want to use Mail Drop?!

Posted on July 20, 2015 and filed under How To, iOS, iPad, iPhone, Mac.