On Aug 17, 2009, at 04:45, Dod wrote:
I usually do it according to fail code 5.x.x or 4.x.x for 4.x.x I
retry later, for 5.x.x I pout them appart to check manually why they
have been rejected.
This is the correct way of handling. As per the RFC, error codes win
the 400 range are "transient errors", meaning that they are temporary,
and the sender should retry eventually; while codes in the 500 range
are "permanent errors". Of course, servers are not required to adhere
to the RFC, but I haven't come across one that does not in this
regard. It's for their own benefit, for they stand to break the
entire system and lose e-mail if they send the wrong response.
"Greylisting" and other anti-spam techniques should result in a 4.x.x
error. Any mail sending application should be smart enough to re-
queue these. 5.x.x errors must not be re-tried without
modifications. In my mail queue server I have a simple algorithm to
attempt to determine the reason for the failure, and sort them so that
they can be manually analysed and corrected if necessary. The most
common errors I've seen are:
1. User not found (account closed)
2. Destination server blacklisted in ORDB
3. Common typo in domain name (e.g. yaho.com, gmail.cmo, etc.)
dZ.
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DZ-Jay [TeamICS]
http://www.overbyte.be/eng/overbyte/teamics.html
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