Test contact form: does the message reach you?

A contact form gives the visitor one signal: the message on the screen. Some forms show that message as soon as the button is pressed, before the server answers. If the server then refuses the message, because it is too long or the file is too large, the visitor still sees thanks and nothing else. The owner never sees the failure either, because their own test message is short and fits every limit. So the first stop is silent, and the owner's check passes.

• Paste a message longer than the text box seems to allow. Does the form send it, or show an error beside the Send button?
• Attach a file just under the size limit and one just over it. Each one needs a clear message, not a silent stop.
• Open the Network tab, press Send and read the status of the request. A thank you after a failed request is a bug.
• Click the email link on a laptop with no mail app set up. Does anything open, or does the link do nothing?

The fastest way to find a silent stop is the browser's own record of the request. Open the Network tab before you press Send, submit the form, and look at the request the page sent. A status of 200 or 201 means the server accepted it. A 400 or 413 means the server refused the message, and a 500 means it broke while handling it. If the page says thanks and the request says 413, the thank you is the bug, whatever the form intended.

Then check the owner's side. Every simulated visitor has a working inbox, so a confirmation sent to the address the visitor typed reaches it. Check your own inbox, the spam folder and the sender name for the alert the form should send you. A confirmation that arrives while your alert never does means the form reached the visitor and not you.

A text box can accept a long message while the server takes only part of it. The server's limit is the one that counts, and when it is passed, the refusal often appears at the top of the page or not at all, far from the Send button. Set the same limit in both places, show it beside the box before the visitor types, and print the reason next to the button when it is passed.

Limits often fail in the wrong unit. A limit counted in bytes runs out sooner than one counted in characters, because accented letters and emoji take more bytes. A message pasted from a word processor can also carry hidden formatting that adds length. Test with a paste as well as with typing, and test one message with an accented name in it.

Some contact pages add a plain email link under the form. A mailto link asks the visitor's computer to open a mail program. On a laptop with no mail app set up, or in a social app's built-in browser, nothing opens, and the visitor reads that as the business not answering. The form is the part you control, so it should not depend on that link working.

Check the link by clicking it on a machine that has no mail app, then check the form beside it. If the link is the only way a visitor can reach you, give it a visible address as text, so the visitor can copy it into any mail program they use. Put that text in the same block as the link, so a visitor who cannot open a mail program still sees it.

Each new spam check, stricter limit or extra field can make the form refuse a message it accepted last week. Send the same message after each change, with the paste and the file, and again on every preview. A paid run can reach a protected preview when you give it a site password or a bypass secret.