Final answer:
James should use mail-merge to send personalized letters to each of his clients, as it allows for automated customization using a template and data source.
Step-by-step explanation:
James is looking to send personalized letters to each of his sales clients, which requires the ability to customize each letter with client-specific information. The best approach for achieving this would be to use a mail-merge feature.
Mail-merge is a process that allows you to create a single document template and then automatically fill in personalized details for each recipient from a data source, such as a spreadsheet or database. This is especially useful for sending personalized documents to a large number of recipients.
While email marketing software, pre-made templates, and bulk messaging platforms can be used for reaching out to multiple contacts, they are not as effective for personalization on a client-by-client basis as mail-merge is. Email marketing software and bulk messaging are typically used for sending generic messages to a wide audience.
Pre-made templates can save time but still require manual editing for personalization. Therefore, for sending personalized letters efficiently to multiple clients, mail-merge is the most suitable option.