Amazon SES connection error - "Authentication Credentials Invalid"

Question

I had setup a fresh EC2 instance with postfix service, configured to send mails via SES . But it fails send mail and shows authentication failure as error in the mail log. Log is attached below :
```
Jun 20 18:35:44 test postfix/smtp[9518]: 9264412CE2D: to=, relay=email-smtp.eu-central-1.amazonaws.com[18.197.243.159]:587, delay=3.5, delays=0.06/0/3.4/0, dsn=4.0.0, status=deferred (SASL authentication failed; server email-smtp.eu-central-1.amazonaws.com[18.197.243.159] said: 535 Authentication Credentials Invalid)
```

I was able to send mail from the same EC2 instance by using SES of a different AWS account.

Both these accounts were configured the same way, with same policies. But still the mails send via the SES service on this AWS account fails.

So I doubt  the emails send out from this AWS account is being blocked by AWS. Can anyone please let me know your thoughts and any solutions/suggestions on the same ?

Answer

Hi, is the new instance in same region and same account? If not, you need to generate new credential as per https://docs.aws.amazon.com/ses/latest/dg/smtp-credentials.html

Amazon SES connection error - "Authentication Credentials Invalid"

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