How to Send a Large Attachment via Email (and Avoid Common Errors)

How to attach a file to an email on desktop or phone

1. Save the exact file you want to send

   Open the file, make your last edits, save it, and close it. If the recipient only needs to read it, export a PDF so the layout stays put and they do not accidentally edit the original.

2. Check the file size before you open your draft

   On Windows, right-click the file and open Properties . On a Mac, use Get Info . On a phone or tablet, open the file details screen. If the file is anywhere near 20–25 MB, expect trouble and switch to compression or a share link before you hit send. ^{2 , 3 , 6}

3. Rename the file so the recipient understands it instantly

   Replace vague names like Scan0001 or final-final with a clear file name such as lease-agreement-signed.pdf or q3-budget-review.xlsx . A clear file name helps both you and the recipient find the attachment later.

4. Open the file once and confirm it is correct

   Make sure it opens, looks right, and does not contain hidden comments or the wrong pages. If the file type is an executable or script, stop and choose a safer format or a link instead; email apps commonly block formats such as .exe , .bat , .js , and .vbs . ¹

5. Start the email and write a specific subject line

   Create a new message, or reply if the file belongs in an existing conversation. Write a subject that matches the file, such as “Signed contract attached” or “Updated floor plan PDF.”

6. Attach the file and wait until it actually appears in the draft

   Use the paperclip or Attach button, then choose the file. On a computer, you can usually browse to the file and select Open or Insert . On a phone, tap the paperclip or plus icon, choose Files , Documents , or Photos , and wait until the file name or thumbnail is visible before you move on. If your phone mail app only shows photos, save the document into your Files app first and attach it from there.

7. Choose attachment or link on purpose

   Use a direct attachment when the file is small and final. Use a share link when the file is large, still changing, or needs view/edit permissions; links keep the message smaller, and an attached copy will not stay synced with later edits to the original file. ^{4 , 5 , 6}

8. Name the attachment in the message body

   Write one plain sentence that tells the recipient what you sent and what to do with it, such as “Attached is the signed lease PDF for review.” Some apps, including Outlook, can warn you if you mention an attachment and forget to add it, but do not rely on that—match the sentence to the actual file shown in the draft. ⁵

9. Check recipients, permissions, and the final draft

   For share links, test access in a private or incognito browser window or review the link permissions before sending. For direct attachments, confirm the correct file name, number of files, and recipient list. If the file is sensitive, remove any extras before you send.

10. Send it, then confirm it left your outbox

    After sending, check that the message left Outbox and appears in Sent with the file or link still visible. If it stalls or bounces, remove the attachment, reduce the size, or resend with a share link instead. ^{2 , 3 , 6}