Currently the form is set up so that visitors can fill it in, submit, and the form goes directly to my client.
He’s now asking for bank details to be added to his website so that visitors can pay directly without him getting involved. However I think it’s a bad idea to have bank details on the website so I’m thinking that if visitors fill in the form, the form gets sent to my client. But at that point can the button ALSO generate an automated email to the sender with bank instructions? Any advice appreciated.
The short answer is yes.
As already mentioned by Doug, not a good idea to send any information that should be secure via email.
You can with foundation set up a second email along with a custom template that could (for example) include wire transfer instructions etc. in the to address you would put the macro for the users email address form field name.