By default your Authorize.net account is configured to send email receipts to your members when a charge is processed. You can disable this or customize those emails from your Authorize.net account settings.

 

First log into your account at https://account.authorize.net.

 

Next click on Account -> Settings:

 

Next click on Email Receipt

 

On the Email Receipt screen you can disable the email notifications or add custom headers and footers — information that will be prepended and appended to the standard Authorize.net transaction receipt respectively. 

  

 
Note: Member Splash pre-fills the email address of the billing contact when payment is made if there is one saved to the account. The member has the option to enter a different email address or delete the field. Obviously no receipt is emailed if no email address is provided.