Newbe Dev Stack

Answer : Bootstrap 4 doesn't include icons (glyphicons are gone), and there are now just 2 validation states ( is-valid and is-invalid ) that control display of the valid-feedback and invalid-feedback text. With a little extra CSS, you can position an icon inside the input (to the right), and control its' display using is-valid or is-invalid on the form-control input. Use a font lib like fontawesome for the icons. I created a new feedback-icon class that you can add to the valid/invalid-feedback . .valid-feedback.feedback-icon, .invalid-feedback.feedback-icon { position: absolute; width: auto; bottom: 10px; right: 10px; margin-top: 0; } HTML <div class="form-group position-relative"> <label for="input2">Valid with icon</label> <input type="text" class="form-control is-valid" id="input2"> <div class="valid-feedback feedback-icon"> ...

Answer : You can't use webfonts reliably in html emails. Some clients might respect and render them, but the majority don't. You can use this website to convert the icons into images, and then simply download the images and upload them to Imgur. From there you can use <img> tags to link to the Imgur images. Edit: A better solution would be to host the images on your own server with the same domain as your email's domain . This will increase the chance of images automatically being displayed on your emails, as they are normally hidden until the user decides to view them. For example, if I used myname@mydomain.com to send emails, I'd host the images on mydomain.com You can embed them as images in your email. You can use fa2png.io which converts the font awesome icons to png of required size as well as color.