USER <username>: Start a new session, replace <username> with your username.
PASS <password>: Authenticate user session, replace <password> with your password.
STAT: Retrieve mailbox status, usually includes the number of emails and the size of the mailbox in the response.
LIST: List all emails and their sizes. Can be used with a parameter to list information of specific emails.
RETR <message_number>: Retrieve the content of the email with the specified number, replace <message_number> with the email number you want to retrieve.
DELE <message_number>: Mark the email with the specified number for deletion. The email will actually be deleted only when the session ends.
NOOP: No operation, usually used to keep the connection or check the connection status.
RSET: Reset the session, undo the deletion markers from all DELE commands.
TOP <message_number> <line_count>: Retrieve the headers of the specified email and the specified number of lines of text. <line_count> is the number of lines of email content you want to retrieve.
UIDL: List emails and their unique identifiers, sometimes used to check the uniqueness of emails.
