Why Amazon SES does not deliver email, though sendEmail return success?

Using SotoSESV2 in a Vapor project: https://github.com/soto-project/soto.git

Following method return success, but email is clearly not delivered hours after the success, how is it possible?

return ses.sendEmail(sendEmailRequest).flatMapAlways { re in
    print(re)
    fflush(stdout)
    switch re {
    case .success:
        print("Welcome message sent to: \(emailTo)")

Email is not in Junk either.

I do not see any bouncing in AWS dashboard or something.

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