Send & Receive Issues

How to Fix Word 2016 Email Sending and MAPI DLL Problems

Maira Mehtab Sep 22, 2026 868 views

Question details

Users are unable to send documents via email or execute mail merges from Microsoft Word 2016, encountering a MAPI DLL or mail application compatibility error.

Product: Microsoft Word 2016
Device & OS: not provided
Scenario: Attempting to send a document via email or perform a mail merge directly within Word 2016.
Observed behavior: Word 2016 fails to send the email and displays an error message regarding a MAPI DLL or mail application communication problem.

Before you start

Verify which version of Microsoft Outlook is currently installed on your computer and ensure you have an active email account configured within it.

Solution 1Recommended

Use Classic Desktop Outlook for Mail Merge

Resolve MAPI DLL errors by switching from the New Outlook to the Classic Desktop Outlook, which fully supports Word mail merge and MAPI email features.

The New Outlook application lacks full support for traditional MAPI functions required by Word 2016 for sending emails and performing mail merges. Reverting to the Classic Outlook application typically resolves this compatibility issue and restores normal functionality.

Verify Classic Outlook Installation

Check your installed applications via the Windows Start menu to ensure that the Classic Desktop Outlook is still installed alongside or instead of the New Outlook.

Set Classic Outlook as Default

Open your Windows Settings, navigate to 'Apps', and select 'Default apps'. Under the Email section, select 'Outlook (classic)' as your default mail client.

Configure Your Email Account

Launch Classic Outlook and verify that it is connected to the correct email account and fully synced with your server.

Restart Word 2016

Close and reopen Microsoft Word 2016, then attempt to send your document as an attachment or run the mail merge process again.

New Outlook Limitations: Microsoft is still actively developing the New Outlook, and it currently does not support all traditional Word mail-merge and MAPI email features.

Free Microsoft Office alternative

Switch to WPS Office for Seamless Document Management

If Microsoft Word 2016 continues to give you MAPI DLL errors or compatibility issues, consider trying WPS Office. It is a lightweight, free alternative that offers seamless compatibility with Microsoft formats and straightforward document sharing tools.

1. Download the Installer: Visit the official WPS Office website and click the download button to get the free installer.
2. Install WPS Office: Run the downloaded file and follow the on-screen instructions to complete the fast installation process.
3. Open Your Documents: Launch WPS Writer and open your existing Word documents directly, without losing any text formatting or layouts.

Highly compatible with Microsoft Word documents (.docx)Lightweight architecture runs smoothly on older operating systemsFree to use with a familiar, easy-to-navigate user interfaceBuilt-in PDF conversion and straightforward document sharing capabilities

microsoft office alternative - wps office

Frequently Asked Questions

What does the MAPI DLL error mean in Word 2016?

A MAPI DLL error indicates that Microsoft Word cannot communicate properly with your default email client. It usually points to a missing file, an incorrect default application setting, or an incompatibility with newer email apps like the New Outlook.

Can I use the New Outlook for Word mail merge?

Currently, the New Outlook does not support all the MAPI functionalities required for Word's mail merge. You must use the Classic Desktop Outlook application to send emails via mail merge successfully.

How do I set Classic Outlook as my default mail client?

Go to your Windows Settings, select 'Apps', then 'Default apps'. Under the Email category, select 'Outlook (classic)' from the list of available applications to ensure Word routes emails through it.

Why is Word 2016 unable to send emails as attachments?

This often occurs if Outlook is not set as the default MAPI client or if there is a mismatch in bit-versions (e.g., using 32-bit Word with 64-bit Outlook). Reconfiguring your default apps or reverting to Classic Outlook usually resolves the problem.

Outlook & Email Problems