Send your first mail merge campaign

Start with a spreadsheet or your Outlook contacts. This guide covers spreadsheet preparation and upload, then links to writing, testing, sending and checking your results.

Updated October 2026

Choose your recipient source

• Spreadsheet: Follow the steps below for Excel, CSV or Numbers.
• Outlook contacts: Follow sending from your Outlook address book, then continue with creating, testing and sending your email.

Available as a video tutorial

Before You Start

Make sure you have everything you need:

• ✅ Microsoft 365 work or school mailbox, SecureMailMerge requires a Business or Education account. Microsoft 365 Personal and Family, Outlook.com and Hotmail accounts are not supported. Check account compatibility.
• ✅ A spreadsheet with recipient data, Excel, CSV, or similar file with at least a “To” column containing email addresses.
• ✅ The add-in installed, If you haven’t already, install SecureMailMerge from the Microsoft Store .
• ✅ IT admin approval (if required), Some organizations require admin approval for add-ins. Learn more about admin approval .

Step 1: Prepare your spreadsheet

Most spreadsheets will work out-of-the-box as long as they have at least one column called “To”. All other columns are optional. Make sure the first line contains the column names.

You can download an example spreadsheet to get you started.

Note: Beware that filters or hidden rows/columns are not supported by SecureMailMerge and will be ignored, resulting in potentially larger campaigns than intended. Always check the number of rows displayed in the sidebar after uploading to verify that the amount corresponds to what you expect.

Step 2. Start the SecureMailMerge Add-In

The add-in works on all platforms that Microsoft 365 supports, but where you will find it may be slightly different. Click the “New Email” button and if you have installed the plugin it will appear in the Apps menu (you can pin it to the standard ribbon from there) or in the add-in menu in older versions.

New Outlook

Other Versions

Outlook for Mac

Step 3. Upload the spreadsheet

To start a new campaign, click the “Upload Spreadsheet” button and select the spreadsheet you would like to use. We support most files from different applications (e.g. Excel, CSV, Numbers).

What your spreadsheet must contain

The file must contain the column names on the first row and at least one column called “To” which contains the email address of the recipient. Also note that columns without a name in the first row are ignored, and rows with no data or an empty “To” cell are skipped.

See here for further troubleshooting for spreadsheets .

If the spreadsheet can be successfully read and parsed you will see the number of records displayed and the name of the file. You can click the “Replace” button in order to change files.

You can also review every recipient and unselect anyone you want to skip before you send.

Step 4. Compose and send your campaign

Next, you can continue with creating your email template using information loaded from your spreadsheet.

→ Click here for our guide on personalizing your email.

That guide takes you through inserting fields, sending yourself a test and starting the campaign. When it finishes, download the send report before starting another campaign.

→ Click here for more help on other use cases (e.g. multiple CC/BCC, personalized attachments etc).