Hi my email management platform improvmx always shows this message, Due to the very low reputation of the sending domain (bubbleapps.io), this message has been blocked
+1 to that , never use sendgrid not just because Bubble shares on free plans but the product is overall is behind the competition. People use postmark I use Brevo
I originally started with SendGrid since it’s built into Bubble, but when I tried to open a new account, I was declined several times across different email addresses. After that, I switched to Bravo (which I had used in WordPress) and haven’t looked back. Bravo offers the same 100 free test emails per day, along with all the capabilities that SendGrid has.
As for the error you’re experiencing, I’m not sure it’s related to the email provider itself. In Bravo, you can easily set up your custom domain right away, and even during testing, use that domain to send emails. Just make sure to add your DKIM records to ensure good deliverability.