In what scenario would you typically use PHPMailer?

PHPMailer is a popular library used in PHP applications specifically for sending emails. It simplifies the process of sending emails using various protocols like SMTP, and it supports features such as HTML emails, attachments, and more. The library enhances the native PHP mail functions by offering better error handling and security options.

Using PHPMailer to send secure emails is particularly important for applications that handle sensitive information or require email authentication. The library supports SSL/TLS for encrypting the connection to the mail server, ensuring that the email content, including any sensitive data, is transmitted securely. This capability makes it an ideal choice for developers who need to implement secure email functionality within their PHP applications.

The other options involve functions that are unrelated to PHPMailer. Sending large files through HTTP pertains to file transfer protocols, creating PDFs is handled by libraries specifically designed for document generation, and optimizing database connections involves database management, which has no relation to email sending. Therefore, using PHPMailer for secure email sending stands out as the appropriate context for its usage.