SmtpMailer: fixed problem with empty response with slow SMTP server

src/Mail/SmtpMailer.php

@@ -213,14 +213,26 @@ protected function write(string $line, int|array|null $expectedCode = null, ?str
 	 */
 	protected function read(): string
 	{
-		$s = '';
-		while (($line = fgets($this->connection, 1000)) != null) { // intentionally ==
-			$s .= $line;
-			if (substr($line, 3, 1) === ' ') {
+		$data = '';
+		$endtime = $this->timeout > 0 ? time() + $this->timeout : 0;
+
+		while (is_resource($this->connection) && !feof($this->connection)) {
+			$line = @fgets($this->connection); // @ is escalated to exception
+			if ($line === '' || $line === false) {
+				$info = stream_get_meta_data($this->connection);
+				if ($info['timed_out'] || ($endtime && time() > $endtime)) {
+					throw new SmtpException('Connection timed out.');
+				} elseif ($info['eof']) {
+					throw new SmtpException('Connection has been closed unexpectedly.');
+				}
+			}
+
+			$data .= $line;
+			if (preg_match('#^.{3}(?:[ \r\n]|$)#D', $line)) {
 				break;
 			}
 		}
 
-		return $s;
+		return $data;
 	}
 }