I did some minor work on an existing website by adding a mailto link in a form tag. The owner tried to use the mailto link by visiting the website on his phone (it is a regular website, not optimized for mobile) and kept getting the ERR_UNKNOWN_URL_SCHEME message. Is there a way to fix this from the webpage? I've seen posts about changing the code in the app or whitelisting certain sites, but I only have access to the HTML website. Any advice would be much appreciated! Thanks.
mailto is a link, not a form post:
<a href="mailto:helpdesk@example.org?subject=a%20simple%20Question">Mail with subject filled out</a>
You can find examples almost anywhere.
If you want form content mailed to some address, this is usually done on the server with a script. Could be done on the client with advanced javascript.