How to adjust Mail Drop minimum file size for Mac Mail


Mail Drop allows user to send larger files over email than typically allowed by uploading the sent file to iCloud from mail app in OS X and the passing the link to download that file onto the recipient.

By default mail drop threshold for mail attachments is 20 MB before kicking in and offering the service, but some email providers don’t allow files over even 10 MB to be sent through their mail servers. With a command you can change the file size limit before Mail Drop is requested for transmitted a file. If you’d like to adjust the minimum file size threshold for sending files over Mail Drop 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 default file size, you can do that too.

Changing the Mail Drop attachment Size Threshold for mail app in OS X :

  • Exit the 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. defaults write minSizeKB 10000.
  • Hit return and then re-launch Mail app.
  • Send any file over 10 MB and Mail app will prompt you to use Mail Drop (iCloud must be enabled on the Mac)

Mail Drop requires using the mail app in OS X with iCloud and OS X 10.10.X and newer versions, the rest is quite simple and just a matter of attaching larger files to an email and selecting to use Mail Drop is by dragging a file on to the mail app icon in the dock which is over the threshold.

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

Defaults write com.Apple.mail minsizeKB 2000. 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.

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