Hey Francis Lupo,
Are both your iPhone and iPad up to date? This could help with Mail issues if not. You can read how to update here:
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. Choose the software update that you want to install. You can choose to stay on iOS or iPadOS 15 and still get important security updates. Or you can choose the option to upgrade to iOS or iPadOS 16.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now.
Update your iPhone or iPad
If that doesn’t help, remove the affected accounts from your iPhone and iPad, restart, then add them back. This could also have an impact on the issue. You can read how here:
1. Go to Settings > Mail > Accounts.
2. Tap the email account you want to remove, then do one of the following:
• If you’re removing an iCloud email account: Tap iCloud, tap iCloud Mail, then turn off “Use on this device.”
• If you’re removing another email account: Turn off Mail.
Note: To remove the email account from all apps on your device, tap Delete Account.
Add and remove email accounts on iPhone
Add and remove email accounts on iPad
Take care.