There are two basic autoresponder triggering methods (subscription to list and date-based-triggers) in MailChimp, but there are so many different ways you can use them.

I’ll show you 4 easy examples anybody can build in the MailChimp interface, plus one clever way to use the API to trigger your autoresponder.

Trigger after subscribing to list:

This is the easiest autoresponder trigger, and the main reason we built our autoresponder tool. Schedule a series of tips and how-to-advice to automatically go out to people after subscribing to your list. In the example above, a wedding planner is sending wedding planning tips to new subscribers to get them interested in her services (here’s a more detailed example). The key here is to show off some expertise without making yourself obsolete. An alternative might be, “Top 10 wedding mistakes” to scare prospects into hiring you. I’m just saying.

Trigger based on a recurring annual event:

This works well for birthdays, anniversaries, or anything you want to happen every year based on a date that your user enters into your signup form. Maybe it’s a car tune-up reminder, or some kind of “bring your widget in for its annual checkup.”  Tip: Send belated birthday autoresponders to stand out in the inbox

Trigger based on a fixed date:

The example above is for a kids summer camp. Just before the session they’re signed up for, an email (or a sequence of emails) goes out with packing checklists, directions, etc.  Works well for travel, too. Just before the big cruise to the Bahamas, send some helpful emails on what to pack, what they’ll be experiencing (send lots of pictures), how to gloat in front of your co-workers,  etc.

Trigger after a fixed date:

In the example above, imagine you host a big event, and 2 weeks after the last day of the event you want to send a survey to all attendees asking for their feedback. Tip: In that survey, you should ask them to opt-in for news about the next big event. Actually, don’t do that. It’ll look so blatant. Hmm, how about in that feedback survey email, you point users to a landing page with pictures from the event, and where other attendees can post comments, pics, videos, and network with each other. Consider services like Crowdvine, or Ning, or even a simple Facebook Fan Page.

API – triggered autoresponders based on hidden date field:

Some users have told us, “I don’t want to send autoresponders based on subscription to a list. I need to trigger them via the API to send to people already on my list.”

Our answer to that is NO.

Autoresponders are very powerful, but they can also be very, very annoying and abusive (to be totally honest, this is why we avoided offering them in MailChimp for so long). In our interface, we deliberately built autoresponders so they’d only go to people who double opted-in to a list.

However, there are a few cases where we think it’s ok to use the MailChimp API to trigger an autoresponder.

You’d basically setup your list, signup form, and autoresponders in MailChimp, but then use the API to pass data into them.

Let’s say you’ve got an e-commerce system, and customers can order small samples from your site. Like carpet or tile or color swatches. The idea is that your product has a tall price tag, so you let them purchase a tiny sample for say, $5. The cool thing about that is you know these buyers are pretty interested if they’re paying money for samples. Anyway, upon purchase of the sample, provide a checkbox in your cart (check out our e-commerce plugins) that lets the customer receive a sequence of free “decorating idea” emails.

Maybe the emails can include inspiring photos from real customers, or perhaps a “Top 10 mistakes” sequence.

The key is to make it optional, and to set expectations about what they’re going to receive. You don’t want to “surprise” your own customers with unwanted emails.

Then, setup a list in MailChimp for customers who ordered samples from your site. Next, create an autoresponder that goes out 2 weeks after a date (the date that they ordered the sample).

Using the API, subscribe buyers to the list, and set their individual “ordered sample” date fields to be the date they purchased their sample. Tip: Set that date field in your MailChimp signup form as “hidden” in case a customer should happen to see their subscriber preferences page.

On a somewhat related note, here’s a tutorial on sending automated transactional emails with MailChimp’s powerful API, and here’s an awesome case study of using dynamic content in those transactional emails.