Mail Merge

On a personal Windows computer, Mail Merge in Word may fail to send emails or connect to Outlook if either:

1. New Outlook for Windows is set as the default mail app, or
2. The scenario matches a known MAPI/mail merge limitation on certain Windows versions.

Check the following:

1. Confirm Outlook type
   • If using New Outlook for Windows, mail merge to email is only partially available and often results in Word completing the merge but no emails being sent and nothing appearing in Sent Items. This behavior matches the issues described where merges appear to run but no messages are delivered.
   • To use Mail Merge reliably, switch back to Classic Outlook and set it as the default mail client. New Outlook is not fully MAPI‑compliant and cannot be used for full mail merge or “Send as attachment” scenarios from Office apps.
2. Verify default mail client
   • Ensure Classic Outlook (not New Outlook) is the default email program in Windows. If New Outlook is default, Word/Excel/PowerPoint features that rely on MAPI (Mail Merge to email, Share via email, etc.) can fail or do nothing.
3. If on Windows 7 / Windows Server 2008 R2 with older Word
   • There is a known issue where Mail Merge in Word 2010/2007/2003 does not work correctly for plain text or attached emails because the recipient is not populated.
   • The supported workaround is to run the mail merge using HTML as the email format:
     • In Word 2010/2007:
       1. Open the mail merge document.
       2. Go to Mailings → Start Mail Merge → E‑Mail Messages.
       3. Select recipients via Select Recipients.
       4. Choose Finish & Merge → Send E‑Mail Messages.
       5. Enter a subject.
       6. In Mail format, select HTML.
       7. Choose the records to send and click OK.
4. If sharing/sending directly from Word/Excel/PowerPoint fails with MAPI errors
   • A “MAPI failure” or “Unable to share” error is typically caused by New Outlook being the default mail client. New Outlook is not MAPI‑compliant, so it cannot be used for mail merge or direct send from Office apps. Use Classic Outlook instead.

If Mail Merge worked on the work computer but not on the personal computer, the most likely difference is that the work PC uses Classic Outlook as default, while the personal PC uses New Outlook or a non‑MAPI client.

References:

• Mail merge in Microsoft Word does not work on a computer that is running Windows 7 or Windows Server 2008 R2
• Classic Outlook mail merge hangs trying to initialize Word
• Merge to Email problem - please help - Microsoft Q&A
• Mail Merge Emails not sent - Microsoft Q&A
• Mail merge to draft in outlook 365 - Microsoft Q&A
• I am unable to share my file either as a presentation or document type or pdf type by none of the microsoft office apps (Word, Excel, Powerpoint). It is continuously showing "Mapi Failure" and "Unable to Share" errors. What can I do? - Microsoft Q&A