The fastest way to attach a file

Open your email in Outlook and click the Attach button — it looks like a paperclip and sits in the toolbar at the top of the compose window. A file browser will open. Navigate to the file you want to send, select it, and click Insert or Open. The file name will appear in the attachment area below the subject line. You can add multiple files this way by clicking Attach again.

If you cannot see the Attach button, you may be using the simplified ribbon view. Look for three dots (⋯) on the right side of the toolbar, click it, and select Show Ribbon. The full toolbar will expand and the Attach button will become visible.

On a phone or tablet, the attachment button is usually a plus sign (+) or paperclip icon near the bottom of the compose screen. Tap it, choose a file from your device, and it will attach automatically.

Key Takeaways

  • The Attach button is a paperclip icon in the compose toolbar; click it to browse and select files from your computer.
  • You can attach multiple files to a single email by clicking Attach more than once.
  • Outlook shows attached files below the subject line so you can confirm they are there before sending.
  • File size limits vary by your email provider, but most allow attachments up to 20 to 25 megabytes per email.
  • If the Attach button is hidden, click the three dots (⋯) in the toolbar and select Show Ribbon to reveal it.

Where the Attach button is in different Outlook versions

In Outlook on the web (the version you use in a browser), the paperclip icon appears in the toolbar above the message body. It is usually near the formatting buttons for bold and italic text. Click it once and a file picker will open.

In Outlook desktop (the program you install on Windows or Mac), the Attach button is in the ribbon at the top. If you are using the simplified ribbon, you may see only a few buttons; click the three dots to expand it. The paperclip will then appear alongside other options like Insert and Format Text.

On Outlook mobile (iPhone or Android), swipe up from the bottom of the compose screen or look for a plus sign (+) near the text field. Tap it to see attachment options, which usually include Photos, Files, or Browse.

Dragging and dropping files instead of using the button

You do not have to use the Attach button. In Outlook on the web and Outlook desktop, you can drag a file directly from your computer into the compose window. Open a file explorer or folder on your computer, find the file you want to send, and drag it into the message area. Outlook will attach it automatically.

This method is faster if you have the file already open or visible on your screen. It works for documents, images, spreadsheets, and most other file types. If the drag does not work, the file may be too large or the file type may not be supported — in that case, use the Attach button instead and Outlook will tell you if there is a problem.

Checking file size before you send

Most email providers limit attachments to 20 or 25 megabytes total per email. If you attach a file larger than that, Outlook will show a warning before you send. You will see a message like "This message is too large to send" or "Attachment size exceeds the limit."

To check the size of a file before attaching it, right-click the file on your computer and select Properties (Windows) or Get Info (Mac). The file size will be listed in the window that opens. If the file is too large, you can compress it, split it into smaller pieces, or use a file-sharing service like OneDrive or Google Drive instead — you can then send a link to the file rather than the file itself.

Outlook on the web sometimes offers to compress large image files automatically. If you see a prompt asking whether to compress, click Yes to make the file smaller so it sends faster.

What happens after you attach a file

Once you attach a file, its name appears in a box below the subject line. You can see at a glance what you are sending. If you attached the wrong file, click the X next to its name to remove it, then attach the correct one.

The attachment stays with the email until you send it. If you close the compose window without sending, Outlook will ask whether you want to save the draft. If you say yes, the attachment will be saved with the draft and will still be there if you open the email again later.

After you send the email, the recipient will see the attachment in their inbox. They can read it to their computer or open it directly in their email client, depending on their email provider and the file type.

Common reasons an attachment will not go through

The most common reason is file size. If your attachment is larger than your email provider allows, Outlook will block the send. The second most common reason is that your internet connection dropped while Outlook was uploading the file. Try attaching the file again and make sure your connection is stable before sending.

Some file types are blocked by email providers for security reasons — executable files (.exe), certain script files, and files that contain macros may not go through. If you need to send a file like this, compress it into a .zip file first, or use a file-sharing service instead.

If Outlook shows an error message you do not recognize, write down the exact message and search for it online along with your email provider's name. The error will usually tell you what went wrong — for example, "This file type is not supported" or "Attachment failed to upload."

Using OneDrive or SharePoint instead of attaching

If you are attaching a large file or a file you want multiple people to edit together, Outlook can link to a file stored in OneDrive or SharePoint instead of attaching it directly. Click the Attach button and look for an option like Browse Cloud Locations or OneDrive. Select the file from your cloud storage, and Outlook will insert a link rather than a copy of the file.

This method saves space in your recipient's inbox and lets you update the file after sending — everyone who has the link will see the newest version. It also lets you control who can view or edit the file, which is useful if the information is sensitive.

Frequently Asked Questions

Can I attach a file from my phone or tablet?

Yes. Open the email in Outlook mobile, tap the plus sign (+) or paperclip icon, and choose Photos or Files. Select the file from your device and it will attach. You can attach photos, documents, and most other files the same way you would on a computer.

What if I forget to attach the file but already sent the email?

If you realize within a few seconds, you may be able to unsend the email — Outlook on the web has an Undo Send option that appears briefly after you send. Click it to pull the email back, attach the file, and send again. This window is usually only a few seconds long, so you have to act fast.

Can I attach a folder instead of individual files?

No, email does not support sending folders directly. You will need to compress the folder into a .zip file first. Right-click the folder, select Send to (Windows) or Compress (Mac), and a .zip file will be created. Then attach the .zip file to your email.

Why does my attachment show as a link instead of a file?

Outlook sometimes converts attachments to links automatically if the file is stored in OneDrive or SharePoint. This is normal and actually saves space. The recipient can still read or view the file by clicking the link. If you want to send a copy of the file instead, you can change this setting in Outlook's options.

Is there a limit to how many files I can attach?

There is no hard limit on the number of files, but the total size of all attachments cannot exceed your email provider's limit — usually 20 to 25 megabytes. You can attach 10 small files or 1 large file, as long as the total does not go over the limit.