503 error in SES with Lambda (.net6)

Question

When I run the lambda (.net 6) code locally pointing to the SES host, it works. But, when I call the lambda function, it returns 503 error and don´t send the email.

Considerations:
   - The lambda function is under a vpc´s public subnet
   - I'm using the .NET MailKit package to send the emails:

public void Send(string to, string subject, string html, string from = null)
        {
            // create message
            var email = new MimeMessage();
            email.From.Add(MailboxAddress.Parse(from ?? _appSettings.EmailFrom));
            email.To.Add(MailboxAddress.Parse(to));
            email.Subject = subject;
            email.Body = new TextPart(TextFormat.Html) { Text = html };

// send email
            using var smtp = new SmtpClient();
            smtp.Connect(_appSettings.SmtpHost, _appSettings.SmtpPort, SecureSocketOptions.Auto);
            smtp.Authenticate(_appSettings.SmtpUser, _appSettings.SmtpPass);
            smtp.Send(email);
            smtp.Disconnect(true);
        }

I´m using the sandbox setting and both (sender and receiver) are verified. I have also created an policy like bellow and attached it to the lambda role:

}
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ses:SendEmail",
                "ses:SendRawEmail"
            ],
            "Resource": "*"
        }
    ]
}

Could anyone help me with this issue please?

Answer

Hi,

The lambda logs can give more insight on the type of the error you are getting. If you are trying to send messages through SES from a Lambda code and the message is received by SES, then you should receive a message ID. If there is no message ID, this means that the messages has not been received by SES at all, and in that case, the lambda logs should give you more insight about the error you are encountering.

Hope this helps!
Mo

503 error in SES with Lambda (.net6)

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