Emails not sending - can't connect to server / receiving works

The title basically. I receive emails fine, sending doesn’t work though and when I go to settings and try reconnecting to the server it fails. Please advise kind strangers.

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online servicesphone

Hi @Aron,
You can start by checking if the settings are the same as given here. Also check send and receiving mails from the eCloud