On 2011-10-19 12:11:28 +0200, Jose-Marcio Martins da Cruz wrote:
What's still lacking in the BCP proposal is a section about the behaviour
of senders MTAs, which, IMHO, causes a lot of problems too.
Some examples of bad things which really causes problems to greylistings :
* Some MTAs from some (big) ISPs, which connects 3 to 5 times within some
seconds and try again only after some hours (some equals something
between 4 to 24 hours).
* Some ISPs using a pool of sending MTAs which IP addresses are randomly
distributed over ranges without any common part. Something like
193.xxx.xxx.xxx followed by 67.xxx.xxx.xxx...
* Some sender MTAs which begins retrying each some seconds (1 to 10)
during some days, and ends being catched by some rate limit mechanism.
* Some sender MTAs change the envelope sender with every delivery
attempt (Yahoo Groups used to do this, but stopped several years ago.
I don't know any recent example). This garantuees that the triple
never matches ...
* Some ISPs use one machine for the first delivery and another for
processing the queue. The "queue processing" IP will get whitelisted
but the "first try" address wont (unless you are lucky), resulting in
a constant delay for every mail.
* Some bad configured or misinterpreted 4xx reply code
Some MTAs (e.g. old versions of Groupwise) don't understand 4xx at all
and treat it like 5xx.
hp
--
_ | Peter J. Holzer | Web 2.0 könnte man also auch übersetzen als
|_|_) | Sysadmin WSR | "Netz der kleinen Geister".
| | | hjp(_at_)hjp(_dot_)at |
__/ | http://www.hjp.at/ | -- Oliver Cromm in desd
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