MergelineHow to mail merge in Gmail with attachments
Updated October 29, 2026
To send the same file to everyone, attach it once in your mail merge tool and it goes out with each email. Mergeline Pro does this for files up to 15 MB in total. For a different file per person, like invoices, put each person’s file link in a sheet column, or create personal drafts and attach files by hand.
Two very different jobs
People mean two things by “mail merge with attachments”. The first is simple: everyone gets the same file, like a flyer, a brochure or a price list. The second is harder: each person gets their own file, like an invoice, a certificate or a ticket.
The second is a common request. One person needed to “send an email to 200 people with a unique pdf attachment” (r/Outlook: mail merge with unique attachments), and another wanted to automate 200 PDF invoices (r/automation: sending 200 PDF invoices). Most Gmail tools handle the first job well and the second one poorly, so it pays to know which you have.
Same file for everyone
Attach the file once in your tool, and it goes with every email. Keep the file small. A large attachment multiplied by hundreds of emails is slow to send and heavy for people to receive. A PDF under a few megabytes is ideal.
In Mergeline Pro you add attachments in the Copies and attachments section. They go with the first email only, not with follow-ups, and the total is capped at 15 MB so Gmail accepts every email.
How to send the same attachment to everyone with Mergeline
- Prepare the file. Export it as a PDF and keep it small. The total for all attachments is capped at 15 MB.
- Open the campaign. Add your list and write the email as usual.
- Add the attachment. In Copies and attachments, add the file. It is sent with the first email only.
- Mention it in the text. “I’ve attached the schedule” tells people the file is expected, not suspicious.
- Send a test. Send yourself a test and open the attachment from Gmail.
- Send. Press send. Each person gets their own email with the file attached.
A different file for each person
There is no clean built-in way to do this in Gmail. Here are the honest options, from simplest to most work.
| Method | Best for | Trade-off |
|---|---|---|
| A link column | Any list size | People click a link instead of opening an attachment |
| Personal drafts, attach by hand | Up to about 30 people | Manual, but you check each email |
| Google Apps Script | People comfortable with code | You write and maintain the script |
Option 1: one link per person
Save each file to Google Drive, Dropbox or your own system, share it with that person, and paste the link into a column like InvoiceLink. In your email write “Your invoice is here: {{InvoiceLink}}”. Each person gets a link to their own file.
This is the most reliable method at any size. Emails stay small, links can be updated if you fix a file, and you avoid sending private files to the wrong person by mistake. Check the sharing settings: each file should open only for the person it is meant for.
Option 2: personal drafts
Mergeline Pro can create a personal draft in Gmail for each person instead of sending. Open the Drafts folder, attach the right file to each draft, read it once more and press Send. For 10 to 30 people this is quick and lets you check every email, which matters for things like grades or invoices.
Option 3: Apps Script
A Google Apps Script can loop over a sheet, find each person’s file in Drive by name and send it. It is free, and many guides show the pattern. You own the code, though, including errors when a file is missing and Gmail’s limits (Google: Gmail sending limits).
Attachment tips that avoid problems
- Name the file clearly: “Acme schedule March.pdf” beats “final_v3.pdf”.
- Prefer PDF. It opens on every phone and keeps your layout.
- Say in the email what the file is and why you sent it. Unexpected files look like phishing.
- Never attach private files to a group send. If each file is personal, use links or drafts.
- Test with your own address first, and open the attachment from Gmail on your phone.
- For large files, share a link instead. Small emails send faster and are easier to receive.
If you send the same document every month, keep a dated copy of what you sent. It saves an awkward search when someone asks for it again.
Questions
Can I use a merge tag in the attachment name?
No. The attached file is the same for everyone. Put personal details in the email text, or use a link column for personal files.
What about Google Drive files?
Share the file in Drive and paste its link in the email or in a column. Check that sharing lets the right people open it, and only them.
Can I send a different attachment to each recipient?
Not as a true per-person attachment in most Gmail tools, including Mergeline. Use a link column, personal drafts or a script.
How do I send a PDF with a Gmail mail merge?
Attach it once in your mail merge tool. In Mergeline Pro, add it under Copies and attachments, up to 15 MB in total.
Are attachments sent with follow-ups?
In Mergeline, no. Attachments go with the first email only, so follow-ups stay light.
Do attachments hurt deliverability?
Large or unexpected files can. Keep them small, mention them in the text, and send them to people who expect them.
Are attachments free in Mergeline?
No. Attachments, Cc and Bcc are part of Pro. Pro is $12 a month or $99 a year.
Sources
- r/Outlook: mail merge with unique attachments
- r/automation: sending 200 PDF invoices
- Google: Gmail sending limits
Facts checked October 29, 2026. Google and other vendors change their limits and prices, so check the source before you rely on a number.
Mergeline does this from your own Gmail. Free for 60 emails a day with merge tags and no branding. Pro is $12 a month or $99 a year for follow-ups, scheduling and attachments.