deleted e mails are gone after 7 days

This is a setting you can change. In Mail, choose Mail > Preferences, click Accounts, then click Mailbox Behaviors. In the section “Erase deleted messages”, choose a setting:

Mail erases deleted messages at the specified time. Select a setting other than Never to avoid exceeding storage limits set by your email account provider.

If you selected None for Trash Mailbox, you can choose to have Mail permanently delete messages automatically.

If your email account provider sets up the server to delete older messages, the messages are deleted regardless of how you change this option.