In the middle of the first signup flow, where I was going through the process of confirming my email I started getting error messages of not beeing able to signin, and a minute later I got this in my inbox:

"Hello,

We appreciate your interest in Twilio SendGrid and your efforts in completing our account creation process. After a thorough review, we regret to inform you that we are unable to proceed with activating your account (****) at this time.

Ensuring the security and integrity of our platform is our top priority, and our vetting process is designed to detect potential risks. While we understand the importance of transparency, we are not able to provide the specifics of our vetting process.

We want to emphasize that our decision is based on stringent security measures and our commitment to the safety of all our users.

Thank you for considering Twilio SendGrid.

Sincerely, Onboarding & Compliance Operations"

I have been in contact with them several times to try to get clarification on the reason behind this, but they will never actually explained why I should not be able to use their service. I just wanted to warn other developers on here about this practice, since an email service can be an important part of a service, a service that Twilio Sendgrid can decide to shut down at any minute without explanation.

I have since started using postmark instead which is working fine for my application.