Grey-listing?

[Jan-Peter Koopmann]

Hi James,

> 2. If anyone is using grey-listing (of any type), what impact is
> there to the sender and how has this been addressed politically
> within your organisation?  
> 
> Question 2 needs a little explanation: the company that pays my
> salary is concerned that senders will recieve a temporary failure
> message if no mail is sent from their MTA to ours within the "known
> MTA timeout".  

That depends on how you configure your grey-listing. If you do not
accept mail from unknown sites for let's say 60 minutes, most customer
MTAs will generate an e-mail to the sender stating that the e-mail has
not yet been delivered. A more reasonable time might be 15 minutes but
again you will find some customer servers that will generate mail even
after 10 minutes etc. This would be a badly configured server most
people would say (and I would agree) but it is up to the server
administrator and the company policy to determine those thresholds.

> The powers that be, are worried some customers may
> percieve this as a flakey mail server at our end given that many
> customers may only contact us once or twice a year.     

Agreed. We do not use greylisting ourselves and strongly advise against
using it to our customers. Main reason: You simply do not know how the
sending server is configured. If their queue-runner tries a resend after
15 minutes (seems to be the default with many MTAs) you might be
all-set. However I would like to get e-mails as soon as possible and
some of our customers rely on e-mails coming in within seconds/minutes
and not hours. If the senders queue-runner is set for 60 minute retry
intervals, each new e-mail will probably take at least 60 minutes to
reach your inbox. That, from my point of view, would be totally
unacceptable. Again: A 60 minute queue-run interval might sound like a
bad idea to most of us, but it is up to the server adminitrator to
determine that interval. Nothing you can do to guarantee sooner
transmission of the mail.

> Are there any other grey-list solutions? 

Sure. Each have the same basic "problem" though.

Regards,
  JP

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