The fields
The email address is a link, so clicking it opens a new message in your mail app.
Edit the details
Click any field on the client page, type and save. Or click Edit Client to change several at once. Clearing a field and saving empties it on the record.A client with no contact email can still be sent invoices and quotes. Choose Custom emails only when sending and type the address yourself.
Next steps
Manage clients
Adding, finding and deleting client records.
Send an invoice
Where the contact email gets used.