I’ve just set up Sendinblue as per the EE guide to allow transactional email. I’ve put the API key and made a test email, which sent fine. After buying a test ticket though, it seems EE is not using Sendinblue SMTP to send the emails: it still get marked as spam, and Sendinblue statistics do not list said EE emails. Did I miss something here?
Do you have any other email related plugins enabled? Such as WP mail SMTP.
When you sent a test email, was that through the Sendinblue plugin or EE’s test email? Event Espresso doesn’t send mail itself, it builds the email and passes it to wp_mail() to do whatever it is set up to do with the email, so if emails aren’t being sent via Sendinblue something else is hooking in and preventing that (such as an SMTP plugin).