MAIL STOPPED WORKING AFTER INSTALLATION OF OS VENTURA

Go to Mail > Settings > Account. Select the email account and under Account Information, make sure the "Enable This Account" is checked. The Server Settings tab is where you can check if you have it set up correctly. It is possible that you will have to enter the password again in this page for you Incoming and Outgoing Mail Servers since you upgraded. If you need more help with the Server Settings, give us the name of your ISP and we should be able to help.

What exactly do you mean by it stopped working?

Does it crash when opened?

Are you not able to send, receive, or both?

Go into Mail's Accounts setting and remove the email account. Then add it back. That often jumpstarts the email in situations like this.

Try opening the Connection Doctor in mail finder menu.

This will show if your connection to each email account is active and running.

You should see all green leds with this running.

It will also show if you’re downloading or uploading mail as well.

It sounds like possibly the email provider or the incoming and outgoing servers not being correct, or having issues.

What were the results of Connection Doctor under the Window menu of Mail?

How about the Connection Doctor pic, it would be helpful.