A feature in our application allows us to send emails from the application itself.

Currently, the UI is nothing complex, it's just a form with a "to", "subject" fields, and a body. The "to" field is also able to currently accommodate multiple email addresses.

When the users receive this email, they will of course see all the other email addresses that the email was sent to.

For privacy purposes and just a general preference by some of our users in general (this is a legal sector so privacy is important), the emails must sometimes be sent individually - even though they'll all have the same subject/body.

What is the most efficient way for our staff to send out these emails?

I've thought about the following approaches:

(A) Allow the user to append additional "to" fields every time they click on the "+Add" button.


  • Straightforward


  • Our staff sometimes needs to copy/paste email addresses in bulk so they would have to individually copy/paste each email into its own "to" field
  • The current "to" field is able to accommodate multiple emails. If you append a new "to" field, does that mean each "to" field will still be able to accommodate multiple emails?

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(B) Add a checkbox for "Send as separate emails" which means the emails will be sent out individually.


  • Efficiency - a lot of times, our staff has to copy/paste email addresses in bulk, so to have a one-click solution to be able to send individual emails is a time-saver!


  • Our staff might accidentally miss clicking this button, hence, will result in recipients being able to see other people's emails.

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  • You could make the box checked by default. Or, better still, make it unchecked but flip the wording and function to "Allow recipients to see each other's addresses" to make the stakes clear. Also, consider BCC. Commented Aug 26, 2021 at 19:10
  • I think go with the Option-B and by default keep the checkbox "Send as separate emails" ticked. That way it will prevent confidential emails being sent out to all accidentally by human error.
    – Ades
    Commented Aug 27, 2021 at 9:11

1 Answer 1


Answer: Prompts

We're dealing with sensitive data here, so we should prompt the user before they try to do something dangerous.

First, reverse the check box from option B. Have the default be sending individual emails and have a toggle to send the email in a single email. As in, option B but reversed. That makes sure the least destructive option is the default, sending individual emails accidentally causes less damage than sending a single email accidentally.

This toggle could have a confirmation prompt: "This will make the recipients' emails visible to each other.", or something along those lines.

If sending only one email is the most used option, then you could move the prompt to the submit button. That removes one click and still keeps some safety, although keep in mind that if sending individual emails is too rare, users might automatically confirm the prompt every time, even in the rare occasion that they shouldn't.

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