To ensure that your Gmail account is fully synced across all of your devices, you will need to make sure that the same settings are being used on each device. Here are the steps you can take to fix this issue:
- On your Mac, open the Mail app and click on the "Mail" menu in the top toolbar.
- Click on "Preferences" and then select the "Accounts" tab.
- Select your Gmail account from the list of accounts and click on the "Advanced" tab.
- Make sure that the "Store deleted messages on the server" option is checked. This will ensure that messages you delete on one device will be deleted on all of your devices.
- Click "OK" to save your changes.
- On your iPhone, open the "Settings" app and tap on "Mail" to access your email settings.
- Tap on your Gmail account and make sure that the "Archive Messages" option is turned on. This will ensure that messages you delete on your iPhone will be archived rather than permanently deleted.
- Exit the "Settings" app and open the Mail app on your iPhone.
- Tap on the "Accounts" tab and select your Gmail account.
- Tap on "Advanced" and make sure that the "Store deleted messages on the server" option is turned on.
- Exit the Mail app and go back to the "Settings" app.
- Tap on "General" and then select "Reset".
- Tap on "Reset Network Settings" to reset your network settings and fix any synchronization issues.
After following these steps, your Gmail account should be fully synced across all of your devices. If you continue to have problems, you may want to try deleting and re-adding your Gmail account on your Mac and iPhone.