[EXIM] locking vs freezing spool files and a NUL approach

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Author: Jeffrey Goldberg
Date:  
To: exim-users
Subject: [EXIM] locking vs freezing spool files and a NUL approach
If you recall, I was having difficulty with mail stuck in a queue for
hosts that never acknowledged a . after data when there was an ASCII
NUL in the data.

Setting up a special transport for some sites I frequently talk to that
are known of have this problem and having that transport have a filter
calling tr was a possibility, but I didn't like the idea of forking a
separate process for thousands of messages when only a few a week really
need it.

So, I wrote a short script which takes a queue ID as an argument and

  (1) Freezes the message
  (2) Edits the data file (replacing NULs with spaces [to keep the same
                          lenght))
  (3) Thaws the message


What has now occured to me is that this might not be the right approach.

Can exim_lock be called on spool files (the specs only discuss it wrt to
delivery points)? Or would "exim -Meb" be the right approach? Basically,
I'm asking

  (1) Is freezing enough to protect me from harm here, or should I lock
      the file instead.


(2) Can exim_lock be used on spool files

  (3) Is there any difference (other than starting a subshell or command)
      between exim_lock and exim -Meb that I should know about.


If the answer is that freezing is enough, then I don't really need answers
to the other two questions.

-j


-- 
Jeffrey Goldberg                +44 (0)1234 750 111 x 2826
 Cranfield Computer Centre      FAX         751 814
 J.Goldberg@???     http://WWW.Cranfield.ac.uk/public/cc/cc047/
Relativism is the triumph of authority over truth, convention over justice.



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