If you Service Autopilot account is integrated with a credit card processor, any time a card is charged the processor will generate a receipt to the Client to confirm a Payment was made. This is a default setting for most processors but it varies for each one.
In your SA account, you have some control over these receipts as well. You can find these under Settings > Integrations.
If you integrate with CardConnect, you have the option to change where the receipt appears to come from:
If the box is checked, the receipt will appear to come from your company via SA rather than from CardConnect. You cannot disable receipts from SA. You will need to contact CardConnect directly to see if this can be done.
If you integrate with OpenEdge, you have the option to disable receipts from OpenEdge:
Authorize.net with CIM
If you integrate with Authorize.net with CIM, there are no receipt settings in SA. You will need to contact Authorize.net to modify those settings.