Which method is used for sending email messages through a standard email server?

The method used for sending email messages through a standard email server is to send the message using the Simple Mail Transfer Protocol (SMTP). This protocol is widely adopted for email transmission over the Internet and allows for the delivery of email messages from the sender's server to the recipient's server. By using the SMTP protocol, this method can effectively ensure that messages are routed correctly and delivered efficiently, regardless of the email client being used by the recipient.

Options that mention sending instant messages or system emails typically refer to different communication methods that may not utilize standard email servers and protocols. The option related to Outlook Mail specifically ties to using the Microsoft Outlook application, which operates using its own mechanism rather than through a standard SMTP-based server, and thus may not be universally applicable for all email communications. Therefore, the method that explicitly refers to leveraging SMTP for sending emails is the most appropriate choice for standard email operations.