Only send posts that have not been sent before; ID of last post is saved in $lastfile; HTML fixes

README.md

@@ -1,6 +1,6 @@
 # xkcd-Mailer #
 
-Takes the first/latest item from the [xkcd](http://xkcd.com/) atom-feed and mails the image and punchline to a specified email address.
+Takes the first/latest item from the [xkcd](http://xkcd.com/) atom-feed and mails the image and punchline to a specified email address, if it has not been sent before.
 
 ## configuration ##
 
@@ -20,20 +20,28 @@ date_default_timezone_set("Europe/Helsinki");
 // Your destination
 $mail = "your@email.com";
 $from = "xkcd mailer <xkcdmailer@example.com>";
+
+// File to write ID of last post to
+$lastfile = "last.txt";
 ```
 
 
 ## crontab example ##
 
-15 minutes over 7am on monday, wednesday and friday.
+Run every hour.
 
-    15 7 * * 1,3,5 /usr/bin/php /full/path/to/xkcd-mailer.php
+    0 * * * * /usr/bin/php /full/path/to/xkcd-mailer.php
 
+This version will check if the last post was already emailed and will only send the post
+if it has not been emailed yet.
 
 ## caveats ##
 
-- Script doesn't check has the feed been updated, possibly causing old strip delivery
+Make sure to set $lastfile to a path that you have write access to.
 
+## changes ##
+
+- 2014-03-30 @wojas added check to see if a post already sent
 
 ## contributing ##