Instapaper Auto-send to Kindle not working

This is a current, unresolved problem: Instapaper does not automatically send new articles to my Kindle every day. This, despite the fact that my Instapaper account is correctly set up to auto-send new articles to my Kindle, and my Kindle account is properly set up to receive them.

Here’s the scenario:

1. There are new unread articles in my Instapaper account that are more than a day old.
2. My Instapaper account is configured to email new articles to my Kindle every day (see above). I have a Kindle 3 wifi-only.
3. I never receive any emails from Instapaper unless I click the Send Now button. Then, the new Instapaper issue is sent and arrives on my Kindle exactly as expected.

The manual sends arrive just fine; ergo: the Kindle email address is properly configured, and the Kindle account is properly set up to receive the emails.

The status just above the Send Now button commonly reads “Your last compilation was sent 4 days ago” even when there are new unread articles sitting in the account.

I conclude that Instapaper simply is not sending the emails for some reason. Any guesses as to why?

Update: Apparently this is a known issue; Wired published an article which says “Unfortunately, for reasons I’m not smart enough to understand, Instapaper can’t automate delivery to your @free.kindle.com address.” This tells us nothing about what causes the problem, only that it’s a known issue and, for whatever reason, nothing has been done about it.

Second Update: — Marco seems to have been working on the problem. On May 25, @Instapaper tweeted: “Sending tomorrow morning’s Kindle auto-deliveries early, now. I think I finally found the bug that prevented so many from being delivered.” Then on May 26: “@jeremyisweary Have you changed your Instapaper username since setting it up, possibly when I moved to requiring emails-as-usernames?” The problem has not yet been solved for me personally, or for others, as seen in the comments to this blog post. Will keep you posted.

Third Update: — I’ve been receiving my unread articles from Instapaper on my Kindle, and it seems the problem has been fixed. On October 5th 2011 (the day Steve Jobs died), @Instapaper tweeted that Marco believed he had fixed the problem. The same day, he said, “By a few hours from now, all deliveries should be made. If you’re one of those who haven’t been getting them, let me know whether you do.” I’ve been getting my deliveries ever since, and so have others.

If you’re still having problems, let us know in the comments!