Using Mail Drop allows you to send larger files over email than typically allowed by uploading the sent file to iCloud from Mail app in OS X, and then passing the link to download that file onto the recipient. The default MailDrop threshold for mail attachments is 20MB before kicking in and offering the service, but some email providers don’t allow files over even 10MB to be sent through their mail servers. Fortunately, with a little command line magic, you can change the file size limit before MailDrop is requested for transmitting a file.



If you’d like to adjust the minimum attachment file size threshold for sending files over MailDrop in the Mac Mail app, you can do so with a defaults command string in the OS X Terminal. If you make a change and decide you’d rather revert back to the default file size, you can do that too.

Changing the MailDrop Attachment Size Threshold for Mail App in OS X

Quit out of Mail app if it’s currently open Open the Terminal and enter the following defaults write command, changing the numbers on the end to represent the size in KB to become the new minimum attachment threshold (the setting below will be 10MB): defaults write com.apple.mail minSizeKB 10000 Hit return and then re-launch Mail app Send any file over 10MB and Mail app will prompt you to use MailDrop (iCloud must be enabled on the Mac)

MailDrop requires using the Mail app in OS X with iCloud and OS X 10.10.x or newer, the rest is quite simple and just a matter of attaching larger files to an email and selecting to use MailDrop as described here. One of the fastest ways to quickly initiate a Mail Drop is by dragging a file onto the Mail app icon in the Dock which is over the threshold.

If you want to revert back to the default MailDrop setting in OS X Mail, just use the following command string in the terminal:

defaults write com.apple.mail minSizeKB 20000

Relaunch Mail app for the change to take effect.

From the sending side of things, MailDrop is only available for use in Mail app, if you use something like web-based Gmail or another mail client as your default email client, you will not have the option to use the service when sending files out. For the recipient, however, it doesn’t matter what email service you use, you’ll get the same download link to get the attachment.

This handy defaults string was passed our way by a reader, heads up to AppleTips.nl for discovering the appropriate syntax.