Normally, sends and receives are stomiles in an internal buffer before being sent to your script. This line of code eliminates the buffering steps. Create a temporary buffer. The buffer is temporary because it is local to the block surrounded by the curly brackets. Read two responses from the server.
Some servers send two reponses when the connection is made.
Send the HELO command. Send the RCPT command to specify the recipient. Send the DATA command. Send the body of the letter. Note that no reponses are received from the mail server while the letter is sent.