Hi JanCarolDemont,
Thanks for coming to Apple Support Communities for help today.
This article will help explain the issue further: If you can’t send email on your iPhone, iPad, or iPod touch.
The easiest way to resolve the issue, is just to remove the account and set it up again. Have a look at these steps:
"Remove your email account and set it up again
- On your computer, sign in to your email provider’s website. Make sure that all of your email is there or make sure that your email is saved somewhere other than on your iOS or iPadOS device.
- On your device, go to Settings > Mail, then tap Accounts.
- Tap the email account that you want to remove.
- Tap Delete Account.
- Add your account again.
If the steps in this article don't help, contact your email service provider for more information."
Have a fantastic day!