Best Mail Merge Tools for Gmail and Outlook (2026)

Mail merge sends one personalised email per row of a spreadsheet, each with a different name, company or figure, all from your own address. The best mail merge tools for Gmail and Outlook differ less on how they personalise text and more on two things a demo hides: the daily sending limit you will run into, and what heavy sending does to your deliverability.

This guide compares the tools that genuinely merge from a spreadsheet through Gmail or Outlook — GMass, Mailmeteor, YAMM, Gmail's own built-in mail merge, Word and Outlook's native merge, and two Outlook add-ins. Every limit here links to the vendor's own page, because these numbers move.

One thing up front: mail merge is not the same as bulk email marketing. If you need to send thousands of newsletters, none of these is the right tool, and the last sections say what is.

The short answer: which tool wins#

For a Gmail power user who wants follow-ups and open tracking, GMass is the most complete. If you want something simpler and privacy-minded, Mailmeteor is the easy pick, and YAMM is the long-standing Google Sheets choice. If you already pay for Google Workspace and want nothing installed, Gmail's own mail merge is built in.

On the Outlook side, the free option is the classic Word-to-Outlook merge on Windows. For a modern add-in that also works in new Outlook, on the web and on Mac, SecureMailMerge processes your list locally. If each recipient needs a different attachment, Mail Merge Toolkit is built for exactly that.

Whichever you pick, the ceiling is usually the same: your sending account. Most of these tools send through your own mailbox, so they inherit its daily limit — 500 messages a day on a free Gmail account, 2,000 on a paid Google Workspace account, and whatever your Microsoft 365 mailbox allows. A few offer their own sending infrastructure for higher volume, which trades your inbox's reputation for reach; verify what each does on its pricing page, because it changes.

How we compared#

We did not run a fresh send test from every tool. We compared them on the capabilities each vendor documents, which is more stable than a one-off deliverability score that shifts with every provider policy update. Five dimensions decide which tool fits.

• Platform — does it work with Gmail, Outlook, or both, and does it need a desktop app, a browser extension or nothing at all?
• Sending limit — the daily ceiling, which is set by your email account, not the merge tool.
• Personalisation depth — merge fields only, or per-recipient subject lines and attachments too?
• Deliverability features — authentication help, unsubscribe links, and whether the tool nudges you toward sending that trips spam filters.
• Packaging — free tier, trial, per-seat or usage-metered. We describe the shape and send you to the vendor for the current price.

Mail merge tools compared#

Here is the shortlist at a glance. The details below were checked in August 2026; verify the specifics on each vendor's page before you commit.

From shortlist to the right fit#

A comparison table tells you what each tool is; it does not tell you which one survives contact with your actual list size and provider. The rest of this guide goes tool by tool, then walks through choosing by your situation — Gmail or Outlook, ten rows or a thousand, plain text or per-recipient attachments.

GMass — Gmail power merge with follow-ups#

GMass is a Chrome extension that turns Gmail into a mail merge and outreach tool. You build a list in Google Sheets, connect it, and GMass pulls each row into a personalised send with merge fields for any column.

Its strongest features are the ones native Gmail merge lacks: automatic follow-up sequences that stop when someone replies, open and click tracking, and scheduling. That makes it the closest thing on this list to a lightweight sales-outreach tool — which is also why it is easy to misuse. The same features that help a genuine one-to-one merge make it simple to send at a volume that trips spam filters.

Because it sends through your Gmail account, a GMass merge is bound by Gmail's daily limit unless you configure its own sending option. Packaging is a free tier to start plus paid plans. Verify current limits and pricing at gmass.co, because both have changed over time.

Mailmeteor — simple and privacy-first#

Mailmeteor is a Google Workspace add-on that merges from Google Sheets or its own editor. It is built around simplicity: pick a sheet, write a template with {{merge}} fields, preview, and send.

Its distinguishing claim is privacy — Mailmeteor states it does not store the content of your emails. It supports open and click tracking, attachments and scheduled sends, without the heavier follow-up automation that GMass carries.

Sends run through your Gmail account, so the same daily limit applies. Packaging is a free tier plus paid plans. Confirm the current free-tier daily quota and paid limits on mailmeteor.com — the free allowance is the number people most often get wrong.

YAMM (Yet Another Mail Merge) — the Sheets veteran#

YAMM is one of the oldest mail merge add-ons and lives entirely inside Google Sheets. You write your campaign as a Gmail draft, mark up merge fields with column names, then trigger the send from the sheet, which fills in as sent, opened or replied.

It handles personalisation, open and click tracking, and reply detection, and it is a comfortable fit for anyone who already keeps contacts in Sheets. It does not add the sequence automation of a dedicated outreach tool.

YAMM sends through Gmail, so Gmail's daily limit is your ceiling, and its own free tier adds a lower daily recipient cap on top of that. Packaging is a free tier plus paid plans; check the current numbers on yamm.com.

Gmail's built-in mail merge — nothing to install#

Gmail has its own mail merge, previously called multi-send mode. Type @ in the compose window to insert merge tags such as @firstname, @lastname, @fullname and @email, or link a Google Sheet and use any column as a tag. A unique unsubscribe link is added to every message automatically.

The catch is availability. It is only on paid Workspace editions — Workspace Individual, Business Standard, Business Plus, Enterprise Standard, Enterprise Plus, Education Standard and Education Plus. It is not on free @gmail.com accounts, and not on Business Starter.

It is deliberately basic: no open tracking, no automated follow-ups and no per-recipient attachments. You can add up to 1,500 recipients to the To line per message, and merge sends count toward your 2,000-message daily limit, capped at 1,500 recipients a day. For a plain, personalised announcement to a known list, it is the least risky option because you install nothing.

Word and Outlook mail merge — the built-in Microsoft route#

The classic Microsoft workflow needs no add-in: your data lives in Excel, your message in Word, and Word sends it through Outlook, one personalised copy per row. It personalises the body and, with merge rules, the subject line — this is the answer to the common search for Outlook mail merge from Excel.

It is free with the Microsoft 365 desktop apps and genuinely capable for letters and simple emails. The limits are real, though. It runs on classic Outlook on Windows, not the new Outlook or the web version; it has no open tracking, scheduling or per-recipient attachments; and each send passes through your mailbox, so your Microsoft 365 or Outlook.com daily limit applies.

If your merge is a straightforward personalised email or a batch of letters, this costs nothing extra and keeps everything inside Office.

SecureMailMerge — a modern Outlook add-in#

SecureMailMerge is an Outlook add-in built for the newer Outlook world: it runs on new Outlook for Windows, classic Outlook, Outlook on the web and Outlook for Mac. You supply a list, mark up merge fields, and it generates the messages.

Its selling point is where the work happens. The add-in processes your spreadsheet on your own computer and hands only the finished messages to Microsoft 365 to send, so campaign data does not travel to its servers. It is listed as a Microsoft 365-certified add-in.

Packaging is free to start plus paid plans. Because it sends through your Microsoft 365 account, your mailbox's own sending limit still applies. Confirm the current free allowance and paid tiers on securemailmerge.com.

Mail Merge Toolkit — for per-recipient attachments#

Mail Merge Toolkit, from MAPILab, is a Windows add-in that extends the native Word, Outlook and Publisher merge rather than replacing it. Its reason to exist is the thing native merge cannot do: send a different attachment to each recipient. If you searched for a mail merge with attachments tool, this is usually the answer on the Outlook side.

It also personalises subject lines, can send merged messages as PDF, DOCX, HTML, RTF or plain text, password-protect PDF and DOCX attachments, and add UTM tags for click tracking. It is actively maintained — version 7.5 shipped in June 2026.

It is a paid product with a trial, and it is Windows desktop only. If your merge needs each person to receive their own invoice, contract or certificate, this is the tool built for it. If you only need personalised text, the native merge is enough.

Gmail sending limits for mail merge#

The most common surprise with mail merge is the daily limit — and it belongs to your email account, not the tool. These figures were checked against Google's own pages in August 2026; confirm them at the links in Sources, because Google adjusts them.

How many emails can I mail merge per day?#

As many as your account allows, minus anything else you send that day. Hit the Gmail limit and further sends are blocked for up to 24 hours; the window rolls, it does not reset at midnight, which is why large merges are spread across several days.

If you routinely need more than a couple of thousand personalised sends a day, mail merge from a personal mailbox is the wrong architecture. That is a job for an email service provider, not a spreadsheet add-in.

Does mail merge hurt deliverability?#

Mail merge itself does not hurt deliverability; sending like a bulk marketer from a personal mailbox does. Two things separate a safe merge from a risky one: volume and authentication.

On volume, Google treats anyone sending more than 5,000 messages a day to personal Gmail addresses as a bulk sender. As of 2026, those senders must authenticate with SPF, DKIM and DMARC, keep their Postmaster Tools spam-complaint rate below 0.10% — and never let it reach 0.30% — and offer one-click unsubscribe on marketing mail. Most merges are far smaller than that, so the bulk rules rarely apply, but the reputation logic behind them always does.

On content, a message that is obviously a template — identical wording with a swapped-in first name — is easier for filters to spot and for recipients to ignore. The merges that land are the ones that read like a real one-to-one email, sent to a list that actually expects to hear from you.

Where AI Emaily fits — and where it doesn't#

A quick, honest note, since you are on our site. AI Emaily is an AI email client, not a mail merge tool. It does not send one personalised message per spreadsheet row to a list, and we are not going to imply otherwise — for that job, pick one of the tools above.

Where it fits is the other half of the same workflow: the replies. A merge that lands generates responses — interested, not interested, questions, out-of-office — and those arrive in your inbox one at a time. AI Emaily sorts them using inbox rules and a Context Brain, and it can draft replies from that context and per-client profiles, not by learning from your sent mail. It writes in your voice, you approve every send, and there is an undo and an audit trail behind each action.

So the split is clean: a mail merge tool sends the campaign; AI Emaily helps you handle what comes back, across Gmail, Outlook and IMAP. We build AI Emaily. There is a 7-day free trial on Pro — a card is required and it is $0 if you cancel before day seven — and there is no permanent free plan.

How to choose for your situation#

Match the tool to the specific shape of your merge, not to a feature count.