SecureMailMerge

What SecureMailMerge is

SecureMailMerge is a mail merge add-in for Microsoft Outlook. It sends personalized emails from your own Microsoft 365 mailbox to a list in a spreadsheet or your contacts, with a different attachment for each recipient if you need one. The homepage calls it "The advanced mail merge add-in for Outlook 365," and it works in the new Outlook, classic Outlook, Outlook for Mac and Outlook on the web, without needing Microsoft Word.

The people who use it, going by the reviews on the site, send invoices, price increase notices, reports, payroll details, recertification forms and small campaigns to clients where regular newsletter software is not a fit. It is made by Sol Inventum OÜ, and the company's founder writes on its knowledge base that he has worked with Microsoft technologies for more than two decades, including almost a decade focused on IT security. The site is available in English, German, Spanish and French.

The product's distinguishing idea is privacy. Spreadsheets and message content "are processed on your computer inside Outlook and sent through your own Microsoft 365 mailbox," and the company says no campaign data is sent to its servers for processing.

How a campaign works

The homepage describes three steps. You prepare an Excel or CSV file with a "To" column and any other columns you want to use, write the message in Outlook with {FirstName} style placeholders, then preview and send. Each recipient gets an individual email from your own account.

Sources and formats:

• Send to a spreadsheet. Supported types include Excel, CSV, TXT, Numbers, OpenDocument, Works, HTML tables, Quattro Pro and Lotus.
• Send to contacts. Pick recipients from your personal or shared address book and personalize with their name, company or department.

Personalization and formatting:

• Placeholders use cells from the spreadsheet or contact details.
• Conditional blocks show different text to different recipients, and fallback values mean "an empty cell never leaves a gap."
• The message keeps Outlook formatting: tables, signatures, images, and Excel's text formatting options. The site says its simple text tags keep merged fields in the same font as the rest of the email, and you can send test emails before the real run.

Attachments and routing:

• Individual attachments. Add a column of filenames to the spreadsheet and upload the files, so each person gets their own invoice or report. You can also attach the same file to everyone.
• Many-to-one mode sends several spreadsheet rows to the same recipient.
• CC and BCC can carry individual values for each email.
• Reply-to routes replies to a shared inbox, a colleague or a processing mailbox.
• Send as an alias, or send from a shared mailbox such as info@ or sales@ once an administrator grants Send As permission.
• Read receipts and high importance flags work as in normal Outlook mail.

Sending controls:

• Recipient review. Every recipient appears in a table you can filter and search, untick anyone to skip, and the count updates live. The selection locks once sending starts.
• Scheduling, marked as new on the homepage, lets you choose a start date, the weekdays and hours it may send, the delay between messages, and a daily cap.
• Pause, resume or cancel a campaign at any time. If Outlook closes mid-run, reopening the add-in picks up where it left off.
• Send report. After each campaign you can download a report of who received which message, with attachments, message IDs and send times.

Limits and sending volume

SecureMailMerge adds no limits of its own on campaigns, emails, recipients or attachment size. What applies is your Microsoft 365 mailbox. The homepage cites Microsoft's Exchange Online defaults of "10,000 recipients per rolling 24 hours per mailbox (recipients, not messages) and 500 recipients per message," and notes these are defaults, not guaranteed capacity, and that administrators can set lower limits. For message size, the site says you get the mailbox allowance, "commonly 35 MB per message and up to 150 MB where your administrator allows it."

Privacy, security and deployment

The "Confidential" section is plain about tracking: "No recipient tracking. No open pixels, no click logging." The trade-off is that there are no open or click statistics; the company's own knowledge base lists "No built-in analytics" among the product's cons. On regulation, the homepage says the add-in is "Designed for GDPR, not certified against it." The resources menu links an IT Security Guide and a Data Processing Addendum.

For IT teams, it is a modern Office add-in that needs neither Word nor COM add-ins nor an installer; it updates itself, and an administrator can deploy it centrally. The site contrasts this with legacy mail merge tools that depend on Word, Publisher and "the decades-old Office merge engine" installed on every desktop. It installs from the Microsoft Store, and the homepage shows 4.9 stars from 71 ratings on Microsoft AppSource.

Guides and extras

The site backs the add-in with a library of how-to material: guides to mail merge in Outlook, mail merge with individual attachments, setting up Excel for a merge, and mail merge for sensitive data, plus a help center, an FAQ and an updates page. Reviewers on the homepage mention the help pages and videos, and one calls the help department "fantastic and responsive." Two free tools, a Signature Designer and an Out-of-Office Designer, sit alongside the product.

Pricing

The pricing section headline is "Simple pricing, for everyone." There are two options:

• Free version. "Every feature, no time limit, no credit card," with unlimited campaigns. It adds a short promotional footer to each email.
• License, billed monthly or annually. It is priced per month (or per year) and per user, with one license per sending email address, reassignable within your subscription. It removes the footer. You can pay by card, PayPal or through your Microsoft 365 subscription.

The page explains that prices are shown in your local currency, may vary by country, and exclude taxes, so the amount appears on the live pricing page rather than as a fixed figure in the text. A reseller licensing program is linked in the footer.

Who it suits

SecureMailMerge suits anyone on Microsoft 365 who needs to send the same message to many people individually, especially with a unique attachment each: accountants, office managers, HR and payroll teams, nonprofits, brokers and small businesses emailing their clients. Because the data never leaves Outlook and there is no tracking, it also fits organizations that handle sensitive spreadsheets and want IT approval to be simple.

For light cold outreach from a personal or shared Outlook mailbox, the scheduling, daily cap and delay settings help keep sending paced. The free version lets you try every feature before paying.

It is not a replacement for a campaign platform. There are no open or click reports, no warm-up or multi-mailbox rotation among its features, and sending volume is bounded by Microsoft's per-mailbox limits. Teams that need analytics or sequences at scale will use it alongside, or instead choose, a dedicated outreach tool.