Reject mail from invalid domains

[Jason Ede]

We use postfix and yes if it was a 550 reject code then we wouldn't use this facility. Have also found recently that if you reject on non fully qualified domain names then alert emails from mcafee's alert manager that send through internet are rejected as the emails aren't correctly formed. The from field gets picked up as empty by postfix.



From: John Wilcock
Sent: Tue 29/05/2007 10:27
To: MailScanner discussion
Subject: Re: Reject mail from invalid domains


Jason Ede wrote:
> Surely it makes sense to at least check if the sender is a fully 
> qualified domain and also that there is an MX record for that domain?

In theory, yes. In practice, poorly configured mail servers are not 
uncommon and sooner or later you will end up rejecting genuine mail if 
you insist on this.

Also, consider what will happens if a sender domain's name servers are 
temporarily unavailable. [With postfix, the default reject code for an 
unknown helo hostname is 450 rather than 554 for precisely this reason].

John.

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