Problem Description
When it comes to sending and receiving email, two key concepts need to be distinguished: RCPT TO and TO. Although both concepts relate to the recipient of the message, they play very different roles in the delivery of the message.
Detailed Introduction
RCPT TO is the instruction used in SMTP (Simple Mail Transfer Protocol) to specify email recipients. When a mail server is ready to send an email, it uses the RCPT TO command to indicate the real address of the email to the recipient mail server. This address is usually used to reach the recipient's mailbox.
The TO field appears in the actual content of the message and tells the recipient who the message looks like it was sent to. This field is at the head of the message and is one of the first lines of information that the recipient sees. The TO field can contain one or more email addresses or even a display name. However, the contents of the TO field can be easily modified, it does not guarantee the true recipient of the mail.
Difference Summary
RCPT TO is a technical instruction for mail delivery in the SMTP protocol. It is used for communication between mail servers and identifies the real recipient address of a mail.
The TO field is a part of the email header and is displayed in the body for the recipient's reference. It indicates the recipient information of the email, but its authenticity needs to be verified by other methods.
Understanding the difference between these 2 concepts helps to better identify the true recipient of an email and avoid spam and phishing attacks. When dealing with important or sensitive emails, it is a common security practice to confirm that the RCPT TO address is consistent with the recipient information displayed in the TO field.
