I am trying to set up a new mail account but it fails to connect to the server. When I checked the nextcloud log I saw:
OCA\Mail\Exception\ClientException: Creating account failed: Error connecting to SMTP server.
[internal function] OCA\Mail\Controller\AccountsController->create('JC Francois', 'jc@proximus...', '', 'imap.proximus.b...', 993, 'ssl', 'pr385988@proxim...', 'PasswordInPlainText', 'relay.proximus....', 587, 'tls', 'pr385988@proxim...', 'PasswordInPlainText', false)