Bobclass does not send email itself. When you send a confirmation, a reminder or a marketing message, Bobclass hands it to the mail app on your device with the message and recipients already filled in — so the address your clients see is whatever your device is set to send from, not something configured in Bobclass.
If messages are going out from the wrong address, the setting to change is on your device.
On iPhone and iPad
Go to Settings → Apps → Mail. There are two separate things to set:
The default mail app. This can be the Mail app that comes with the iPhone or iPad, or another app such as Gmail or Outlook.
The address messages are sent from. In the same screen, scroll to the Composing section and set Default account at the bottom.
Once Default account matches your studio address, messages sent from Bobclass will go out from it.
These steps cover iOS and iPadOS. If you send client messages from a Mac or an Android device, the equivalent setting lives in that device's own mail settings — contact us at support@bobclass.com if you need a hand finding it.