[Python-Dev] Patch making the current email package (mostly) support bytes

Barry Warsaw barry at python.org
Thu Oct 7 20:37:48 CEST 2010

On Oct 07, 2010, at 04:40 AM, Stephen J. Turnbull wrote:

> > And the email API currently promises not to raise during parsing,
> > which is a contract my patch does not change.
>Which is a contract that has historically been broken frequently.
>Unhandled UnicodeErrors have been one of the most common causes of
>queue stoppage in Mailman (exceeded only by configuration errors
>AFAICS).  I haven't seen any reports for a while, but with the email
>package being reengineered from the ground up, the possibility of
>regression can't be ignored.

I'm fairly certain that most of the modern causes of this are post-parse
modifications of the message.  IOW, in Mailman's architecture, we try to parse
the raw data into a Message object tree very early in the pipeline, and then a
pickled version of that gets passed between the queue runners.  If the initial
parse fails, there's almost literally nothing Mailman can do with the original
data other than delete it.

Where we've gotten into trouble before has been things like adding the Subject
prefixes and such.  That seems like application logic that the email package
can't really get involved with, and indeed Mailman has built up a raft of
defense for failures of this kind.

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