how do you ensure emails are always snt from the same addre

If you are using Apple Mail, go to Preferences, select Composing, note there is an option Send New Messages from, go to that option and select the email address you want to be used for sending emails.

Roy Bradshaw wrote:

Hello. Thanks for the message, I have found it on my Mac Pro, do you know what to do on an iPad.

I don't have a modern iPad (I have an older one) but under iOS for iPhone there is a "Default Account" setting under Mail Settings. But that is not setting the default for sending, it may not accomplish what you are looking for. I don't think the iPad has the same analogous setting as exists on the MacOS.