Should confirmation e-mail be the default?

Question

I run a website where people can book appointments. The e-mail address field is optional, and next to this is a checkbox to receive a confirmation e-mail. The confirmation e-mail contains a code to alter the appointment afterwards. This code is also displayed on screen after making the appointment, so people can write it down. Currently, the checkbox is not checked by default but it appears that people often forget to check the box and cannot change their appointment afterwards.

My question is: should the option to receive a confirmation e-mail be checked by default?

The reason why I didn't was to avoid spamming people, although one might argue that when people enter their e-mail address, they can expect to receive an e-mail. Also, the e-mail address can be used after the appointment to send additional information (with consent of the person), so the more people enter their information, the better. When they see the box checked, they might be more reluctant to do so.

Answer 1

Let's compare the convenience of both options

With email:

• User has to input email
• User gets code + dates in their inbox
• User can verify appointment date at any time
• User can easily change date

Without email:

• No email input!
• Additional input: Write down appointment date
• Additional input: Write down code to change date
• User cannot be sure if what they've written down is correct without going to your website

Overall, providing an email is the much more convenient option for everyone* involved.

The reason why I didn't was to avoid spamming people

Sending a singular email with the dates someone has entered for an appointment hardly is spam. In fact, transactional emails like this typically aren't optional, as a quick search in your emails for "order" will indicate.

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* That said, there may be even more convenient methods than email. Depending on your audience, people may prefer SMS, physical letters, fax, or telephone reminder calls over receiving emails. The way to check this is if they bother giving you their email in the first place - you can be fairly sure that people typing in their email are reasonably comfortable with using such a system.

Answer 2

In the absence of researching with your specific users/product, I would say:

(1) Ask for an email address and make it required

(2) Because of (1) you can kill the checkbox

(3) Send an email confirmation as well as playing back on the confirmation page

(4) Research whether you need to provide an alternative route for users who do not have an email address