support.microsoft.com › en-gb › officeUse mail merge for bulk email, letters, labels, and envelopes Excel spreadsheets and Outlook contact lists are the most common data sources, but any database that you can connect to Word will work. If you don't yet have a data source, you can even type it up in Word, as part of the mail merge process. For details about data sources, see Data sources you can use for a mail merge. Excel or Outlook