A main document in a mail merge contains data, such as names and addresses.

Yes, it contains names and addresses

Explanation:

Mail Merge includes bulk letters, names, addresses, emails and envelops etc.

Mail merge primarily enables automating the process of sending bulk mail to customers, subscribers or general individuals. Mail merge works when a data file is stored that includes the information of the recipients to whom the letter is to be sent. This file can be a spreadsheet or database file containing separate fields for each different type of information to be merged within the letter.