fputs($fp, "QUIT\r\n");
fclose($fp);
if(substr($line, 0, 3) != "250")
{
//mail server doesn't recognize
//this address, so it must be bad
$error = $line;
return(FALSE);
}
else
{
//address recognized
return(TRUE);
}
}
$error = "Unable to reach a mail exchanger!";
return(FALSE);
}
if(verifyEmail("[email protected]", &$error))
{
print("Verified!
\n");
}
else
{
print("Could not verify!
\n");
print("Error: $error
\n");
}
?>
SMTP servers precede each message with a numerical code, such as the 250 code
mentioned above. When first connecting with a server, any number of 220 messages are
sent. These contain comments, such as the AOL servers' reminders not to use them for
spam. No special code marks the end of the comments; the server simply stops sending
lines. Recall that by default the fgets function returns after encountering the maximum
number of characters specified or an end-of-line marker. This will not work in the case of
an indeterminate number of lines. The script will wait forever after the last comment.
Socket blocking must be turned off to handle this situation.
When set_socket_blocking turns off blocking, fgets returns immediately with
whatever data is available in the buffer. The strategy is to loop continually, checking the
buffer each time through the loop. There will likely be some lag time between
establishing a connection and receiving the first message from the server. Then, as 220
messages appear, the script must begin watching for the data to stop flowing, which
means the server is likely waiting for a command. To avoid the situation where a server is