I want to allow my users to add email recipients in a text area by just writing their addresses manually or copy & paste them from somewhere - email addresses are separated via a comma or new line.

How do you validate an email address?

If it's an incorrect address, let's say, john.doe@example,com, how do you tell the user that it's incorrect?

If it's an incorrect address, let's say, john.doe@example,com, how do you tell the user that it's incorrect?

A) Show them a notification under the text area?

If you've got multiple mistakes, you can always expand the notification underneath and make it scrollable. enter image description here

B) Offer a tooltip / notification?

This is option would be very frustrating when the user has multiple mistakes. enter image description here

C) Do you offer any validation at all?

AFAIK, email validation isn't 100% accurate whatever you do - you can never have all the edge cases thought through. So, you might end up creating a nuisance if you don't validate a legitimate email.

  • It's a good question but alas, it would only get you opinionated answers. Personally, I prefer a blend of A and C. Highlight blatant format errors, repetitions, etc. with a generic error message underneath and forget about checking the existence of an email id or the site extension Nov 28, 2018 at 5:37
  • You should edit your question to be more about what is good or bad, UX wise about these options, rather than which one people would choose, because that encourages opinion-based answers. Nov 28, 2018 at 7:22
  • Thanks for the info on this! Will edit the question ASAP. Nov 28, 2018 at 7:49

2 Answers 2


You have made some valid points.

However, option C makes the most sense. Many organizations have a practice where bulk emails are sent, and it may inlvolve users copy pastying more than 100-200 email addresses in one go. In that case, option A is a big NO-NO. You don't want the user to individually search for the wrong addresses and sit and fix them.

Also, you're correct. Email validation cannot be 100% accurate, so all big email clients will let you enter any email address. However, I think you could combine option B and C. For example -

enter image description here

You could use colors to represent validation states. If 100% valid (if it satisfies all the pre-determined validation criterias) it can be a green pill, and if it doesn't satisfy all criterias, it can be an orange pill (to indicate that something MAY be wrong with that email address) with a question mark icon (or any icon/no icon) which can provide some useful information on mouse hover (tap on mobile). This should not, however, prevent the user from sending the email.

  • 1
    Thanks a lot for the info! I was also thinking about exploring coloured pills and adding a help icon in case we have trouble validating that email. Completely agree that this should not prevent the user from sending the email. This should just be a visual notification that something is wrong / unsure. :) Nov 28, 2018 at 7:49

Usually, you find "best practice" by looking at what everyone else is doing. So look at how your email clients behave. Gmail doesn't seem to do any validation. And here's Outlook:

enter image description here


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