The basic steps for attaching a file

To attach a file, open your email or messaging program and start a new message. Look for a button or icon that shows a paperclip, a plus sign, or the word "Attach" — the location depends on which program you use. Click that button, then find the file on your computer or phone that you want to send. Select it and confirm. The file name will appear in the message, usually in a separate area below the subject line or message body.

The exact steps vary slightly between Gmail, Outlook, Apple Mail, and messaging apps like WhatsApp or Slack. The principle is the same: you tell the program where the file lives, the program finds it, and it bundles the file with your message when you send.

Key Takeaways

  • Every email and messaging program has an attach button — usually a paperclip icon — that opens a file browser on your device.
  • You can attach multiple files at once by selecting more than one file before confirming, though some programs have size limits.
  • Large files may fail to send or take a long time; if a file is over 25 MB, cloud storage or file-sharing services are usually faster.
  • Once you attach a file, it stays attached until you send the message — closing the program without sending will lose the attachment.

Where to find the attach button in common programs

Gmail shows a paperclip icon at the bottom of the compose window. Click it to open your file browser. You can also drag and drop files directly into the message area.

Outlook (desktop and web) displays an "Attach" button in the toolbar at the top of the compose window. Web Outlook also accepts drag-and-drop. The Outlook mobile app uses a paperclip icon at the bottom of the message.

Apple Mail on Mac has a paperclip icon in the toolbar. On iPhone or iPad, tap the arrow icon in the message field, then select "Add Attachment." Messages (Apple's texting app) uses a plus sign to add photos, videos, or documents.

WhatsApp shows a paperclip or plus icon next to the message field. Slack displays a plus sign in the message box. Both let you attach files, images, or videos before sending.

File size limits and what happens when files are too large

Most email services accept attachments up to 20 to 25 MB per message. Gmail allows up to 25 MB per file. Outlook allows up to 20 MB on the web and up to 112 MB in the desktop app. If your file is larger, the send button will either fail silently or show an error message telling you the file is too large.

For files larger than 25 MB, use cloud storage instead. Upload the file to Google Drive, Dropbox, OneDrive, or iCloud, then share a link to that file in your message. The recipient can download it from there without hitting email size limits. This method also works better for sending multiple large files at once.

Attaching multiple files at once

You can attach more than one file in a single message. After clicking the attach button, hold down Ctrl (Windows) or Command (Mac) and click each file you want to send. Then click "Open" or "Confirm." All selected files will attach to the message.

On phones, most apps let you tap the attach button multiple times to add files one at a time. Some messaging apps like Slack let you select multiple files in one browser window before confirming.

Keep the total size in mind: if you are attaching five files that are each 10 MB, you will hit the 25 MB limit. In that case, use cloud storage or send the files in separate messages.

What to do if an attachment fails to send

If your message fails to send and you see an error about file size, the file is too large for email. Remove the attachment and use cloud storage instead. If the error mentions the file type, your email provider may block that kind of file for security reasons — this is rare but happens with executable files (.exe) or certain script files.

If the send button does nothing and no error appears, close the message without sending, restart your email program, and try again. Sometimes a temporary connection problem prevents the send from going through. If the problem continues, try attaching a smaller test file to see whether the issue is specific to that file or a broader problem with your account.

Drag-and-drop attachment in web email

Gmail, Outlook on the web, and most other web-based email services let you drag files directly into the message area instead of using the attach button. Open your email, start a new message, then drag a file from your computer's file explorer (or Finder on Mac) into the message window. The file will attach automatically.

Drag-and-drop is faster if you have your file browser open already. It does not work on all phones or tablets — mobile email apps usually require the attach button method.

Attaching files from cloud storage or your phone

You can attach files that are already stored in cloud services. In Gmail, click the attach button and select "Google Drive" to attach a file from your Drive without downloading it first. Outlook offers similar options for OneDrive files. This saves time and keeps your message size smaller.

On phones, the attach button usually opens your phone's file browser or photo library. You can attach photos, videos, or documents stored on your device. Some apps also let you attach files directly from cloud storage — look for a cloud icon or a "More options" menu in the file browser.

Frequently Asked Questions

Can I attach a file to a text message?

Standard text messages (SMS) cannot carry file attachments. If you want to send a file via text, use a messaging app like WhatsApp, iMessage, Telegram, or Signal instead. These apps work over data or Wi-Fi and support photos, videos, and documents.

What happens to an attachment if I close the email without sending?

The attachment is lost. Most email programs save a draft of your message, but the attached file is not part of that draft. If you close the message, you will need to attach the file again when you reopen the draft.

Can the person I send a file to open it on their phone?

It depends on the file type and what apps they have installed. Photos and videos open on any phone. Word documents, PDFs, and spreadsheets need the right app — most phones have built-in viewers for these. Specialized file types may not open without specific software.

Is it safe to attach files to email?

Email is not encrypted by default, so anyone with access to the email server could theoretically see the file. For sensitive documents, use cloud storage with password protection or a file-sharing service that encrypts the link. For everyday files, email is fine.

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

Some email programs, especially Gmail, convert large attachments to cloud storage links automatically to save space. The recipient can still download the file — it just comes from cloud storage instead of being embedded in the email. This is normal and does not affect whether they can open it.