Is there a parameter to set to send HTML e-mails from WordPress 5.5.1 / CiviCRM 5.29? Plain-text e-mails are send and tokens merged but HTML doesn't get sent.
Is this related to css (even if I use literal around code)?
EDIT 1: I was able to send very simple HTML but some more complex (but not so complex) code blocks CiviMail
EDIT 2: I've tried with CiviCRM default templates 'Sample CiviCRM Newsletter' and nothing gets sent :-(
EDIT 3: If I create a simple HTML message with the CKEditor, then it gets send.
EDIT 4: I've tried enabling/disabling WordPress' PostSMTP extension and CiviCRM'S Flexmailer, Mosaico and CiviMAIL extensions and component without success.