You can create a link on your website, and after clicking it default email client will be opened.
The most simple mailto format is mailto:my@email.com
But you also can provide default body text, subject and add some people in cc or bcc.
This is example
mailto:me@email.com&cc=you@email.com&bcc=somebody@email.com&subject=Hello&body=Hello_it_is_body
the format is very simple
Parameter
Value
cc
here you can add person in carbon copy
bcc
here you can [...]