Click here to jump to instructions for how you might get past the MESSAGE TRUNCATED error.
There once was a time when all e-mail messages contained nothing but ASCII characters. Then as computers got better at producing such things, people decided that they wanted to be able to send images and sounds through e-mail. And MIME (Multipurpose Internet Mail Extension) was invented as a standard way to send “binary attachments”. And life was good.
But even before most people had software that could extract these MIME attachments, dark forces recognized that MIME could be used not only to distribute porn, but also to distribute malicious executable code such as viruses and worms. And the dinosaur list got nailed a few times, either because we had subscribers with infected computers or because we had subscribers with friends who had infected computers. After a few incidents where working viral code was distributed through the list, we slammed the door on viruses.
Unfortunately, the only door we have available for such things is big, heavy, and non-discriminatory (meaning it equally discriminates against any and all MIME attachments).
Any time the dinosaur list receives a message containing a MIME attachment, that attachment is stripped off and replaced with the infamous “---REMAINDER OF MESSAGE TRUNCATED---” error. This is automatic and happens even to messages that are sent to the list but not distributed through it (for instance, a lot of the spam I get consists of messages bounced to me by the listprocessor because the sending address is not a subscriber; if such messages contain attachments, those attachments are removed even though the message will not go to the list).
However, because there is still plenty of software that cannot deal with MIME attachments, a lot of software that sends MIME encoded mail sends along with the MIME version, a plain text alternative. The listprocessor does not touch the plain text. What happens when you receive such e-mail depends upon the characteristics of your mail reader. What follows is a text version of a message recently sent through the DML. I’ve included much (but not all) of the header lines, and color-coded some key pieces.
Some explanation... The red line (MIME-Version: 1.0) tells your mail reader that the message has MIME encoding. The orange line specifies the type of encoding, (Content-type: multipart/alternative;), and what separates the different parts (boundary="Boundary_(ID_REIhQ2hvKDOcEcZ0ECDT0w)"). The “alternative” indicates that the message contains different versions of the same thing. The filter at USC should change that line, because after the attachment has been pulled out, the parts are no longer truly alternatives. Unfortunately, I am told that the script is not flexible about such things and cannot be changed (in any case, I can’t do anything about it).
Anyways, notice that there are three boundaries (color coded in green). These tell your mail reader where the two alternatives lie, one between the first and second boundaries, and the other between the second and third boundaries. Most mail readers assume that you will want to see the second alternative, because usually it is the version that has html code or fancy fonts or other things to make the text look prettier. And so many of you see only the error message. Many of you have mail readers that will show you or at least allow you to inspect both alternatives. Hence it seems like some people are getting messages that others are not.
If your mail reader showed you both alternatives, you would have seen the URL (the contents of the first part: http://ucsdnews.ucsd.edu/newsrel/science/12_08_chicken.asp) and the MESSAGE TRUNCATED error message. Presumably the original second part contained the URL along with html code to make it clickable from any mail reader that allows you to follow embedded links. I can’t really tell you that for sure, because all I got was what is contained above...
In actuality, everyone is getting the same thing (essentially like the example above). But some people have mail readers and sufficient technical knowledge to allow them to see the text. And some don’t. We at DML management are caught between a rock and a hard place. We can turn the filter off, which would mean more messages would get through. But along with those would be some viruses or worms. Or we can leave the filter on, and things stay as they are, with many messages being unread and unarchived.
A brief interlude... Since some people don’t seem to want to believe me, I offer some examples: Pine, AppleMail, Netscape, Gmail, and Juno. Write to me if you want to add instructions for other mail packages.
We activated the filter after viruses got through two (or was it three?) times in quick succession. Since then, incidences of viruses “sent” by actual subscribers have been rare -- probably about once or twice a year. I personally hate the thought of sending working viruses to 600 computers, but perhaps at this point the cure is worse than the disease. Let me know if you have a strong opinion on the matter.
Before I let you go, I should also mention that not all of the software people use will send plain text alternatives. In some cases, e-mail sent to the dinosaur list contains only an encoded attachment. The filter strips those out too, and the result is that no one receives anything except for the MESSAGE TRUNCATED error. That is why some times you get nothing even though at other times you see the error and yet still get the intended message text.
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Mickey Rowe (mrowe@lifesci.ucsb.edu)
P.S. There is, of course, one more alternative. If all participants would make certain that they only send plain text, the filter would never touch their messages. As we have been saying for years, you can find out how to configure your mail-sending software at:
http://www.expita.com/nomime.html.
or: