1. Craigslist combines listings that come in at once into a single email. That's fine, but they truncate the results (... SNIP...) if a lot of listings come in. Why? Are they worried about exceeding your incoming email size limit with an all-text email?
2. Sometimes they send emails with zero results. Again, why?
3. Maybe not an issue in NY or SF where good apartments rent minutes after listing, but even in Seattle's hot housing market duplicate listings are a big problem. I've seen the same listing posted multiple times per day for days on end. All of these listings appear in Craigslist's email alerts, so you have to wade through them all. While the author didn't address this in his bot's code, I see filtering out duplicate or "already seen, not interested" listings as the biggest benefit to a home-made solution like this.