Hey there BluesMan,
Thanks for reaching out to Apple Support Communities. I understand you’re trying to set up Trash to not empty the email automatically. You can change the behavior by following the steps below:
You can set how long deleted emails stay in the Trash mailbox.
- Go to Settings > Passwords & Accounts.
- Tap your email account, tap Mail (below Advanced), then tap Advanced.
- In the Advanced settings, tap Remove, then select a time interval.
Note: Some email services might override your selection; for example, iCloud doesn’t keep deleted emails longer than 30 days, even if you select Never."
Delete and recover emails in Mail on iPhone
I hope this helps.