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<form> in Superhuman

Not supported <form> is not supported in Superhuman.

Works in 10 of 21 · partial in 4 · not supported in 7

Which clients
Works
Gmail, Gmail Android, Outlook iOS, Outlook Android, Apple Mail, Apple Mail iOS, Yahoo Mail Android, Samsung Mail, Thunderbird, AOL Mail
Partial
Gmail iOS, Outlook 365, Outlook (New), Outlook for Mac
Not supported
Outlook Classic, Yahoo Mail, Yahoo Mail iOS, HEY Mail, Proton Mail, Fastmail, Superhuman

Your reader in Superhuman sees the email without <form>, even if it looks right where you tested it.

The fix for Superhuman

Replace embedded form with a link to a hosted form

after 
<table role="presentation" cellpadding="0" cellspacing="0">
  <tr>
    <td style="background-color: #6d28d9; border-radius: 6px;
               padding: 12px 32px;">
      <a href="https://example.com/subscribe"
        style="color: #fff; text-decoration: none;
               font-family: Arial, sans-serif;
               font-weight: bold;">
        Subscribe Now
      </a>
    </td>
  </tr>
</table>
Show the original
before 
<form action="/subscribe" method="POST">
  <input type="email" placeholder="Email" />
  <button type="submit">Subscribe</button>
</form>

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What Superhuman does with <form>

@emailens/engine 0.18.22 on the original code

Superhuman strips form elements.

Your next question

Every feature in Superhuman · <form> in every client

Questions

How many email clients support <form>?
It works in 10 of 21, partial in 4, not supported in 7.
What do I use instead of <form> in Superhuman?
Replace embedded form with a link to a hosted form.

To see what else in your email Superhuman does not support, paste the whole email.

The checker needs a computer screen.

caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 10 Sep 2019 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping