How to attach a whole folder to an email on a Mac

Email carries files, not folders, so a folder has to become a single zip file before it can travel. Mail on a Mac will usually do that for you when you drag a folder into a message, but compressing it yourself in Finder first lets you check the name and the size before you send. If the zip is too big for the mail servers involved, Mail Drop or a shared link gets it there instead.

What Mail does when you drag a folder in

Drag a folder from Finder onto the body of a message in Mail and, on recent versions of macOS, Mail typically compresses it and attaches the result as a zip named after the folder. The details have varied between versions, so look at the attachment before you send. If it shows a name ending in .zip, the folder is in there as one file.

Relying on that has two drawbacks. You do not see how big the zip is until it is already in the message, and the attachment takes whatever name the folder happened to have, which is how people receive a file called untitled folder 2.zip.

Webmail in a browser is less predictable. Many attach buttons and drop areas on webmail sites accept files only and quietly ignore a folder, and what the rest do depends on the site and the browser. Zipping first removes the guesswork wherever you send from.

Zip the folder yourself first

1. In Finder, rename the folder to what the recipient should see, such as Kitchen quotes March. The zip takes the folder’s name.
2. Right-click the folder and choose Compress “Kitchen quotes March”.
3. Kitchen quotes March.zip appears beside the folder. The folder itself is untouched.
4. Select the zip and press Command-I. The Size line in the Get Info window tells you whether it will fit in an email (more on limits below).
5. Drag the zip onto the message body, or choose File > Attach Files… in Mail and pick it.

How to attach a file to an email in one drag covers the drag itself, including what to do when the file and the message are never on screen at the same time.

Do not expect the zip to shrink much if the folder holds photos, video or PDFs; those formats are already compressed. Folders of text documents and spreadsheets usually get noticeably smaller. Either way, the zip’s real job is to turn a folder into one attachment.

Size limits and Mail Drop

Every email provider caps the size of a message, and both the sender’s and the recipient’s limits apply. Many sit somewhere around 20 to 25 MB. Attachments are also encoded for the trip, which makes them roughly a third larger, so a 20 MB zip can bounce from a server with a 25 MB cap.

Mail has a way around this called Mail Drop. When an attachment looks too large, Mail asks “Would you like to send this attachment using Mail Drop?” and explains that Mail Drop can deliver a large attachment using iCloud, along with how many days it will stay available. Click Use Mail Drop and the zip goes up to iCloud; the recipient gets your message with a download link in place of the attachment. Apple’s documentation describes a 5 GB limit for Mail Drop attachments and says they do not count against your iCloud storage.

To check it is switched on, open Mail > Settings, click Accounts, select the account, and look on the Account Information tab for Send large attachments with Mail Drop. Because it works through iCloud, expect it to need the Mac signed in to iCloud.

The link expires, so Mail Drop suits a one-off delivery, not a folder the other person will come back to for months. For that, or for anything over the Mail Drop limit, share the folder from iCloud Drive instead. How to send a whole folder from a Mac covers the Collaborate link and the other routes.

What the recipient gets on Windows

A zip made by Finder opens on Windows without extra software. Double-clicking it on the PC shows the contents like a folder, and Extract All copies them out to a real folder. Extracting is worth doing before anyone edits a file, because a document opened from inside a zip can open as a temporary copy whose changes are easy to lose.

A few Mac traces may come along for the ride:

• A folder called __MACOSX, holding files whose names start with ._. These carry Mac file details that Windows has no use for. They are safe to ignore or delete.
• .DS_Store files, if the folder had them. Finder keeps each folder’s view settings in one. Also safe to delete.
• Names Windows refuses. A Mac allows characters in file names that Windows does not, such as a question mark or an asterisk. A file named Final?.docx can fail to extract on a PC. Rename anything like that before you compress.

Mail’s Edit menu has an Attachments submenu with a Send Windows-Friendly Attachments option, which, as the name suggests, is meant to make loose attachments behave better on a PC. A Mail Drop link, for its part, opens in any web browser, so it works the same for someone on a PC.

Holding the zip while you write the message

The fiddly part is often not the zip but the timing. You make the zip in Finder, then still have to find the right thread in Mail, write the message, and get the compose window and the zip on screen together.

Ledge gives the zip somewhere to wait. Drag it up to the notch at the top of a MacBook screen, or the top center of the screen on a Mac without one, and it lands on a shelf. Write the message at your own pace, then press Option-Space or click the notch and drag the zip off the shelf into the message body. The message receives the file, which is the form an email can use; dropped on a terminal instead, the same item would arrive as its path. You can gather the zip and a couple of loose files from different folders on the shelf first and bring them across together.

Ledge does not compress anything and does not send mail. Finder makes the zip, Mail does the sending, and Ledge has no account and no cloud of its own.

Questions

Why did my email with a folder attached bounce?

Most likely the zip, once encoded, was larger than one of the mail servers allows. Check its size with Command-I, then send it with Mail Drop or as a shared iCloud Drive link.

Does zipping the folder change the original?

No. Compress writes a new .zip beside the folder and leaves the folder exactly as it was. You can throw the zip away once the email has gone.

Can I put a password on the zip before emailing it?

Finder’s plain Compress command does not ask for one. Terminal can make a password-protected zip, and this guide to password-protecting a zip covers how, along with why standard zip encryption is weak.

Can the recipient open the zip on a phone?

Usually, yes. The Files app on an iPhone or iPad expands a zip when you tap it, and most Android phones include a file manager that can open one.