ietf-smtp
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Re: retry question

2008-08-05 17:49:31

ned+ietf-smtp(_at_)mrochek(_dot_)com wrote:

Overall, the implementation where it attempts to satisfy all and keeps
trying in new sessions until the very last one is resolved, would be
more difficult, wasteful and prune to error - especially in a list
distribution.  But of course, its not impossible to do.

The names we have for this three-state logic in our code are, with apologies to Sergio Leone, "good" (2yx), "bad" (5yz), and "ugly" (4yz).
> There's a reason we call it the ugly case.

Speaking one implementation only:

For our list server MTA making the distribution, we have two transport modes - Direct Smart Host SMTP server vs the old UUCP/UUCICO transport mode.

The latter option it will make a copy for each member. So we have customers who will use that old mode, but this time saving the .XQT/CMD/DAT files in the queue that the SMTP router eyeballs for outbound. This gives them the singular sends and retries.

But in direct SMTP connect mode, a 1 copy for all method, the 5xx response will auto-unsubscribe the member, and 4xx just skips them for the specific transaction - "'tough titty!' said the cow the cat to the cow when the cow went dry." Doesn't unsubscribe them but they don't make that one distribution.

But as you said, the ugly has been when the 4xy should really be permanent. Our solution is a list moderator defined error limit option (default 3) when it begins to auto-unsubscribe the 4xx member distribution response.

Of course, when there is the real but rare rare false positives, users will report and compliant.

So I don't think it has been a big issue that required attention.

--
Sincerely

Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com

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