Oops, fix logic

protocol/imap/imap.go

@@ -123,7 +123,7 @@ func (c *Conn) LoginSASL(username, password string) error {
 	enc := base64.StdEncoding.EncodeToString(b)
 
 	return c.cmd(fmt.Sprintf("AUTHENTICATE PLAIN\r\n%s", enc), func(line string) error {
-		if strings.TrimSpace(line) != "+" || !strings.HasPrefix(line, "* ") {
+		if strings.TrimSpace(line) != "+" && !strings.HasPrefix(line, "* ") {
 			return fmt.Errorf("unexpected IMAP auth response: '%s'", line)
 		}
 		return nil