Thanks Peter.  In fact my problem messages weren't really emply, they just appeared so when viewing with Thunderbird.  I now seem to have solved the problem, or at least have a work-around.  If I allow TB to "Select this Folder for Offline Use", the message shows up straightaway.  Without checking this option there is an error message in the TB Error Console and there is no such error message there when I check the offline use box.  I will probably pursue this error message among the Thunderbird forums.  Anyway, as most people here suggested, I don't think that the problem was with Mercury.  It's just that the evidence was very ambiguous.

Thank you

Gordon

I have raised the issue of certain messages being received as empty (no body, no attachments) a couple of times over the past year and despite many helpful suggestions and actual test collaboration, I have still failed to solve the problem.  This problem only occurs with a small fraction of incoming messages, though these often include those originating from my office, so it is inconvenient.  The problem only occurs when using Thunderbird as the client.  OE, for example, doesn't have the problem.  Also, if I send the same message from my office to both my normal ISP address (from which all messages are POP'd to my home Mercury 4.62 server) and to my GMail IMAP account (which is accessed directly by Thunderbird, not via Mecury), Thunderbird reads the GMail version correctly but the version via Mercury has an empty body and no attachments.  The message information isn't actually lost by Mercury/Thunderbird as, if I drag the message to a local folder, it is then viewable.  I now have a little more evidence regarding this problem.  I have recently installed Kubuntu 9.0.4 and along with this, the Linux version of Thunderbird.  The empty message problem shows itself just the same as when using a Windows version of Thunderbird.  BTW, the problem has consistently shown itself over several versions of Thunderbird.  I have also viewed these messages with Kubuntu's default e-mail client, KMail, and there is no empty message problem.

I am now speculating that the problem may be with my particular installation of Mercury, so I am thinking of re-installing it.  I can see several options for doing this.  Can I install the same version of Mercury on top of the existing installation (or will this only proceed if one is trying to apply a true upgrade)?  Alternatively, I could install a new installation Mercury in a new folder.  Either way, I would like to retain my existing mail store and the various files for Content Control, Filtering, Blakc/White lists etc.  Can I copy everything over to a new folder and just replace the existing Mercury .exe?  Of course, in doing so, I may carry over the problem to the new folder, if the problem is with my Mercury instalation, but not in the .exe.

Any help would be appreciated.

Thank you

Gordon

Add to global filters following rule (will be in file: rules.mer)

If not expression body matches "*" Delete ""

Peter - Thank you for the reply.  Can you tell me what this addition to the global filters is actually doing?  I already use global filtering extensively and I want to be sure that this addition introduces no clashes with other rules.  I presume that I will have to place this rule first in the list, or it could be ignored, because of the path taken through the rule-set.

Gordon

You don't say, but I am assuming you are connecting to Mercury via IMAP.

I find that Thunderbird regularly gets its local cache index out of whack, which has the effect of showing blank messages in the list.

Mostly, doing a 're-index' of the folder fixes it, but I have had occasions where a close & reopen of Thunderbird was required to refresh the list.

Peter's suggested rule will delete any messages passing through the server with a blank body, which I don't think is your issue as they show up OK in other clients.

This also points to Thunderbird as the problem not Mercury, or rather the Thunderbird IMAP client's interaction with the Mercury implementation of the IMAP protocol (there are a variety of 'interpretations' of IMAP). There may be some Thunderbird settings that can be adjusted to resolve the issue, but I haven't found them yet [:)]. There are a lot of options available in the IMAP protocol and not all apply to all server implementations.

I don't think reinstalling Mercury (or using a separate copy) will help.

I have a fairly big archive of old mail on a linux machine that is running Courier IMAP and thunderbird doesn't seem to have the same issues with that. Administering it is a bit more involved though, which is why it is a single user archive & Merc is our production IMAP server [:)]

Thanks DLN.  You are correct.  I definitely don't want to delete these empty messages.  I am not yet convinced which side, client or server, is causing the problem.  It seems to me that the options are:

The problem is with TB.  The fact that OE and KMail can see the messages may support this, but the fact that sending the message via GMail IMAP is readable tends to go against this conclusion.  However, it may be that TB is checking something or not ignoring something in the mail message that OE and KMail do not, and TB doesn't like what it is seeing.  Neverthless, there must (maybe) be something different about the message from GMail as opposed to that from Mercury that it causing TB to act differently.

The problem is with Mercury.  Is Mercury generating something or not including something that is critical from TBs point of view?  However, some months ago,  I sent the same message to Thomas and myself he was able to see message content with his installation of TB and I found the message to be empty with my TB installation.

My first reaction was to compare the bytes of the two messages from GMail andf Mercury.  However, if I found a significant difference, why was Thomas able to read a message that I could not?

When I was testing this a while ago, I did find some problems in the TB error log.  I can't remember what these were now, but I think that it was something to do with font colour.  I'll run the test again and see if an error shows up.

Gordon

An IMAP server session log from Mercury will give the complete conversation (you may have fun trying to decipher it though [:)]).

Not sure how to get the same from Tbird / Gmail.

I seem to recall that setting Tbirds cached connections to 0 from default of 5 definately improved the situation.

[quote user="GordonM"] Thanks DLN.  You are correct.  I definitely don't want to delete these empty messages. [/quote]

The global filter will only delete inbound and outbound messages that have no body. This one only does good and elliminates fault finding in later steps like POP3, IMAP and spam fighting, and should IMO have been there per default, as an empty message is pointless. You can combine it with another filter, that triggers if Subject and Body is empty.