Detailed answer
Mailto requests a configured email handler, while tel requests a suitable calling handler.
They do not silently send a message or place a call in every environment. Provide readable contact information that users can copy. Encode query values such as an email subject correctly when building the URL.
Example
<a href="mailto:help@example.com?subject=HTML%20question">Email support</a>
<a href="tel:+15550101000">Call +1 555 010 1000</a>
Understanding the behavior
Mailto and tel ask the operating system or browser to open a configured handler. They do not send an email or make a call automatically. Some devices have no suitable application configured, so the visible address or number should remain understandable.
Practical implementation notes
Encode mail subjects or other URI parameters correctly. Avoid placing private data in a prefilled message URL, and provide another contact route when completing the task depends on a handler being available.
How to check it
Activate it on a device with an appropriate handler and provide copyable contact text.
Expected result
The handler is offered; no hidden message or call is sent automatically.
Watch out: A mailto link is not a reliable server-side contact-form handler.
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