530 Authentication required

Question

SES has started to reject some of my outbound emails with the error: 530 Authentication required

```
This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

host email-smtp.us-east-1.amazonaws.com [18.210.31.252]
    SMTP error from remote mail server after MAIL FROM::
    530 Authentication required
```

Other emails still go through fine though. I have only one set of SES credentials and they have not changed. This looks like an issue at AWS.

Answer

The problem is that TLS negotiation is timing out, so my server tried to send the email without authenticating itself. I forced my server to require TLS for email-smtp.us-east-1.amazonaws.com so that it won't try to send the email unauthenticated.

But the TLS shouldn't be timing out, this looks like an issue at AWS.

530 Authentication required

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