Once you mark a visit completed, you can generate a "service report" and send it to your client. To do this, open the visit and then click on the "..." button located next to the "reopen" button. In the dropdown you will see a "Generate service report" link. When you click the "Generate service report" link a PDF file of the service report will be generated and added to that visit as an attachment.

You can then send an email notification to the client and add the service report pdf as an attachment.