Why Word Mail Merge to Email Adds Quoted-Printable Encoding Selectively

When you use Word Mail Merge to send emails directly, some recipients report that special characters such as accented letters, em dashes, or smart quotes appear as garbled text like =E9 or =2014. This happens because Word selectively applies Quoted-Printable (QP) encoding to the email body based on the content and the mail client that processes the merge output. Understanding why Word chooses QP encoding for some messages but not others helps you control the final appearance and avoid unreadable emails. This article explains the technical trigger for Quoted-Printable encoding in Word Mail Merge to email, how it affects different character sets, and how to prevent encoding mismatches before sending.

How Quoted-Printable Encoding Works in Word Mail Merge

Word does not generate emails natively. When you perform a Mail Merge to email, Word uses the Messaging Application Programming Interface (MAPI) to send messages through a MAPI-compliant mail client such as Outlook. The mail client, not Word, decides whether to apply Quoted-Printable encoding to the message body. However, Word influences that decision through the character set and formatting it passes to the client.

Quoted-Printable encoding is defined in RFC 2045 as a method to represent non-ASCII characters in email headers and bodies using only printable ASCII characters. It encodes bytes outside the ASCII range (decimal 0–127) as an equals sign followed by two hexadecimal digits. For example, the character é (U+00E9) becomes =E9. Word selectively triggers QP encoding when the document contains characters that the mail client considers unsafe for 7-bit SMTP transport. This happens most often when:

• The merge document includes characters above U+00FF, such as curly quotes, em dashes, or accented Latin letters.
• The mail client is configured to use a legacy character encoding like Windows-1252 or ISO-8859-1 instead of UTF-8.
• The merge fields pull data from a source that contains non-ASCII characters, even if the main document uses only ASCII.

The Role of the Mail Client in Encoding Selection

Word passes the email body as a MIME message to the mail client. The mail client examines the body content and chooses an encoding. If the body contains only ASCII characters, the client sends the message as 7-bit without QP encoding. If the body contains any byte with the high bit set (values 128–255), the client applies QP encoding to preserve those bytes during SMTP transit. This is why the encoding appears selective: a merge that produces emails with only plain ASCII text uses no encoding, while a merge that inserts a single curly apostrophe or accented letter causes the entire body to be QP-encoded.

Steps to Prevent Unwanted Quoted-Printable Encoding in Mail Merge Emails

Use the following methods to reduce or eliminate QP encoding artifacts in your merged email messages. Apply the method that best matches your document structure and mail client.

Method 1: Set Word Document Encoding to UTF-8

1. Open Web Options in Word
   Click File > Options > Advanced. Scroll to the General section and click the Web Options button.
2. Change the encoding setting
   In the Web Options dialog, click the Encoding tab. In the Save this document as list, select Unicode (UTF-8). Click OK twice to close all dialogs.
3. Save the main merge document
   Press Ctrl+S to save the document. This encoding change applies to the current document only and tells the mail client to handle characters as UTF-8, which reduces the chance of QP encoding for Latin-script characters.

Method 2: Remove Non-ASCII Characters from the Data Source

1. Open the Mail Merge Recipients list
   In Word, go to Mailings > Select Recipients > Use an Existing List. Choose your data source and click Edit to open the Mail Merge Recipients dialog.
2. Filter or replace non-ASCII characters
   Click Filter to create a rule that excludes records with special characters, or use the Find Duplicates feature to identify problematic entries. Alternatively, edit the data source file in Excel or Notepad and replace characters like curly quotes with straight quotes and em dashes with hyphens.
3. Update the merge fields
   After cleaning the data, click OK and save the main merge document. Run a test merge to confirm that no QP artifacts appear in the email body.

Method 3: Send Emails as Plain Text Instead of HTML

1. Change the mail format in Outlook
   In Outlook, go to File > Options > Mail. Under Compose messages, set the Compose messages in this format list to Plain Text. Click OK.
2. Adjust the merge document formatting
   Because plain text does not support bold, italic, or colored text, remove any formatting from the merge document. Use simple line breaks and no tables or images.
3. Run the Mail Merge to email
   In Word, click Mailings > Finish & Merge > Send Email Messages. The To, Subject, and Message body fields now use plain text, and the mail client does not apply QP encoding even if the body contains accented characters.

If the Encoding Problem Persists After the Main Fixes

Word Mail Merge to Outlook 365 Still Shows =XX Characters

Outlook 365 may apply QP encoding even when the Word document uses UTF-8 if the message body exceeds a certain length or contains multiple non-ASCII characters in a single paragraph. To work around this, split long messages into shorter paragraphs using two carriage returns between each block. Outlook treats each paragraph as a separate MIME part, and shorter parts are less likely to trigger QP encoding for the entire body.

Mail Merge to Gmail via SMTP Shows Garbled Text

When you use a third-party SMTP add-in for Word Mail Merge to send through Gmail, the add-in may handle encoding differently than Outlook. Check the add-in documentation for an encoding override option. If none exists, export the merged messages to a text file using Mailings > Finish & Merge > Edit Individual Documents, then paste the content into Gmail manually. This bypasses the Word-to-SMTP encoding pipeline.

Recipients Using Older Email Clients See =20 at Line Breaks

The =20 artifact appears when a soft line break (space at end of line) is encoded as a space character. This is a side effect of QP encoding applied to HTML-formatted messages. Switch the mail format to plain text as described in Method 3 to eliminate =20 artifacts entirely. If plain text is not acceptable, reduce the line length in the Word document to under 76 characters per line, which is the maximum line length for QP encoding, and the client will not insert =20 placeholders.

Item	Plain Text Email	HTML Email
Encoding applied by mail client	7-bit ASCII; no QP encoding	QP encoding when non-ASCII bytes present
Character support	ASCII only; accented characters become =XX	Full Unicode if UTF-8; otherwise Windows-1252 with QP
Formatting allowed	None (no bold, italic, colors, tables)	Full HTML formatting
Best for	Simple notifications, internal messages	Marketing emails, newsletters with design

You now understand why Word Mail Merge to email applies Quoted-Printable encoding selectively based on character content and mail client behavior. To prevent encoding artifacts, set the document encoding to UTF-8, clean non-ASCII characters from the data source, or switch to plain text email format. For messages that require HTML formatting, test a sample merge with the actual recipient email addresses and check the raw source for =XX patterns before sending the full batch.