Sander Holthaus - Orange XL writes:
The following log-entry caught my attention:
Jan 26 03:45:11 ********* courieresmtpd: started,ip=[***.***.**.***]
Jan 26 03:45:18 ********* courieresmtpd: error,relay=***.***.**.***,msg="540
TLS not available.",cmd: STARTTLS
Jan 26 03:45:26 ********* courieresmtpd:
error,relay=***.***.**.***,from=<[EMAIL PROTECTED]>: 517 Syntax error.
Somebody tries to connect over SMTP, issues a STARTTLS to which I reply TLS
not available. But what's up with that last line?
It's a double-bounce from either Courier or Qmail.
Double-bounces should always be delivered locally. Double-bounces should not be send somewhere else; that may cause various bad things to happen.
Therefore, both Qmail and Courier fabricate a rather obnoxious return address on double-bounces that nearly everyone will reject out of hand.
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