How do I send invoices or certificates to many people, each with their own file?

Updated October 29, 2026

A workflow that holds up

1. Name each file after the person or number, like “Certificate - Jane Doe.pdf” or “INV-1042.pdf”.
2. Upload them to one Drive folder.
3. Share each file with that person’s email address only.
4. Copy each file link into the matching row of your sheet, in a column called FileLink.
5. Write the email: “Hi {{FirstName|there}}, here is your certificate for the spring course: {{FileLink}}”.
6. Preview several rows and click a few links to make sure they match the names.
7. Send.

Why links beat attachments here

• Each email stays small, so it is less likely to be held by a company mail filter.
• If you spot a mistake in a file, you fix the file and the link still works.
• Sharing by address means only that person can open it.

One Reddit user needed to send “200 PDF invoices” this way. At that size, links plus a merge is far faster than attaching by hand.

When you really need an attachment

Some people expect the PDF in the email itself. For up to about 50, use Mergeline Pro’s drafts mode and attach each file before sending. For larger batches, an Apps Script that attaches a Drive file per row is the free option. See mail merge with Apps Script.

After sending

Keep the sheet as your record of who got which file. If someone says the link does not open, check that the file was shared with the exact address in that row, not with an older one.

Read the full guide: Mail merge with attachments

Related answers

• Can I send a different attachment to each recipient in a Gmail mail merge?
• How do I send a PDF attachment with a Gmail mail merge?
• Can I create personalized Gmail drafts to review before sending?

Sources

• r/automation: sending 200 PDF invoices
• r/Outlook: mail merge with unique attachments

Facts checked October 29, 2026. Google and other vendors change their limits and prices, so check the source before you rely on a number.