On 05/10/12 10:40, Chris Green wrote:
As per the subject line, do most SMTP servers (as in systems 'out there' which send me mail) behave reasonably sensibly when my SMTP server is temporarily not functioning?
Greylisting, which works pretty well as a spam reduction solution, relies on the fact that most legitimate SMTP servers behave properly, whilst most spammers mail "servers" don't. So the likely effect of an outage is that most spam that would otherwise have reached you during the outage will be lost, but your legitimate email will be fine.
There's a difference between being literally "not there", and being there but sending a "temporarily unavailable" response (which is what greylisting does), but I doubt that mail servers generally distinguish between them?