Senders for marketing mails sent by campaigns have to be configured on Brevo.
How about senders for transactional mails form an external web app using SMTP? Is it also necessary to declare all of them on Brevo or can you just send along?
@ahudavert Thanks for your reply. However, I’ve added this question to a running support ticket and the answer to it was the exact opposite: No, for transactional mails, the senders don’t have to be declared in the UI.
To make sure I tried it without declaring the senders and the mails are both delivered and look okay in terms of DMARC and friends, provided the domain is configured correctly on Brevo and the required DNS recs have been created.