Hi mark,   
      
   On 2014-04-23 21:18:57, you wrote to me:   
      
    WvV>> First, I have never noticed a false positive. There were false   
    WvV>> negatives, when the messages were too old to be in the dupe base.   
      
    ml> what determines the age of "too old"?? simply the number of entries in the   
    ml> database, the age of the post by creation date or the age of the post by   
    ml> arrival time??   
      
   Number of entries.   
      
    WvV>> FMAIL.DUP      Contains  the database  with signatures  of   
    WvV>> messages                used by  FMail to  detect duplicate   
    WvV>> messages.  FMail                keeps track of the last 16384   
    WvV>> messages.   
      
    ml> wow... understandable to a point... it brings up the question of what the   
    ml> records consist of to fill 64K with only 16384 posts...   
      
   A CRC32 (4 bytes) per post. 16K * 4 = 64K.   
      
    WvV>> FMAIL32.DUP    The 32-bit version of the duplicate detection   
    WvV>> file.                It is  capable of  keeping track of  more   
    WvV>> duplicates                than the 16-bit DOS version. (max.   
    WvV>> 9999*1024).   
      
    ml> this seems inconsistent with the previous statement... one says "16384   
    ml> messages" whereas this one seems to say 9999 messages with 1024 bytes   
    ml> (bits?) per entry...   
      
   This one is used by the 32bit versions of FMail. The 9999 is the maximum you   
   can configure in the "Dups recs (x1024)" setting. The 1024 is not bytes, but   
   entries.   
      
    WvV>> Ignore MSGID   
      
    WvV>>           Normally FMail uses the MSGID of a message (if present)   
    WvV>>          for duplicate detection purposes. In some cases, this   
    WvV>>       may cause problems when different messages are having   
    WvV>>    the same MSGID: one or more of these messages will be   
    WvV>> marked as duplicates although they are not. If you are   
    WvV>> frequently experiencing these problems, try setting this   
    WvV>> switch to 'Yes'.   
      
    ml> that would seem to defeat the purpose of MSGID... especially if FMail is   
    ml> expecting the MSGID to be unique across all message areas... in fact, this   
    ml> brings up one of the flaws in the MSGID portion of the relevent FTSC   
    ml> standard document... there is no specification of uniqueness across all   
    ml> message areas or if the uniqueness is per message area... there are   
   several   
    ml> well known packages that operate on the "per area" basis which then causes   
    ml> false positives in other packages... for that matter, there are some well   
    ml> known packages that maintain duplicate databases on a per area basis   
    ml> instead of one attempting to cover all message bases...   
      
   That's what this setting is for. If you experience false positives, you can   
   turn of the MSGID based dupe checking...   
      
    WvV>> Dups recs (x1024) (32-bit mode only, start FSetupX with "/32")   
    WvV>>           Number of signatures of messages that are stored on   
    WvV>>      disk.   
      
    ml> is this true for all supported OSes? this shouldn't, IMHO, be   
    ml> necessary... the tool should be able to detect which environment it is   
    ml> running in and use the necessary means/methods/capabilities...   
      
   This setting is to specify the number of dupe records used in 32bit versions   
   of fmail. But since FSetup doesn't know which version of the fmail.exe program   
   you are using, you will have to specify (on the commandline) you want to   
   configure the special settings for the 32 bit versions.   
      
    WvV>> So it depends on the version you are using and your settings. In   
    WvV>> the .DUP file a crc32 of some parts of the message (depending on   
    WvV>> your settings) is stored. If you want to know more about the   
    WvV>> techincal details of that, look in the source:   
      
    ml> thanks... but i asked so that   
      
    ml> 1. non-coders would have a simple straight forward answer   
      
   I know you know your way around code. And you asked the question.   
      
    ml> 2. myself and others would not have to try to wade through alien code   
      
   You rather have me do it?... My time is limited, and for me the code is   
   "alien" as well. Time I spend on "support", can't be spend on development.   
      
   Remember I'm not the original coder, so most of the code is still unfamiliar   
   to me. And I don't know any of the motives of the original coder why he did   
   the things the way he did them... The advantage of open-source is, everyone   
   can find out the details for himself, if he is interested enough.   
      
    ml> then there's the question of does the duplicate detection have any   
    ml> effect on the messages being passed on to other systems...   
      
   Dupe checking is done before messages are tossed to other systems, as it   
   should!   
      
   Bye, Wilfred.   
      
   --- FMail-W32-1.68.1.61-B20140411   
    * Origin: FMail development HQ (2:280/464)